According to the National Agricultural Aviation Society (NAAS), without the use of crop protection products to control insects, weeds, and diseases, crop yields per acre will drop by more than 50 percent. The first aerial application of insecticide occurred in 1921 and was a huge success. In today's economy, all aircraft that are classified as aerial applicators do more than just apply insecticide; they also spread seed and apply fertilizer. From the information given above, which of the following CANNOT be validly concluded?

Introduction / Context:
This critical reasoning question focuses on understanding conditional statements and their logical consequences. The passage tells us what happens to crop yields without crop protection products and describes the capabilities of aerial applicator aircraft in the modern economy. The task is to identify which option cannot be validly concluded from the given information. This requires careful attention to the direction of implication and to the difference between a statement and its converse or inverse.

Given Data / Assumptions:

• According to the NAAS, without the use of crop protection products to control insects, weeds, and diseases, crop yields per acre will drop by more than 50 percent.
• The first aerial application of insecticide in 1921 was successful.
• In today's economy, all aircraft that are classified as aerial applicators do more than just apply insecticide; they also spread seed and apply fertilizer.
• We must find which option is not a valid logical consequence of these statements.

Concept / Approach:
The key logical structure from the NAAS statement is: if crop protection products are not used, then yields drop by more than 50 percent. Symbolically, Not used leads to drop greater than 50 percent. The valid contrapositive is that if yields do not drop by more than 50 percent, then crop protection products have been used. However, the converse, which would say that if yields drop by more than 50 percent then products were not used, does not necessarily follow. For aerial applicators, the statement is that if an aircraft is an aerial applicator, then it can perform several tasks including applying fertilizer. The contrapositive of that statement is also valid.

Step-by-Step Solution:
Step 1: From the NAAS statement, we have: if no crop protection products are used, then yields drop by more than 50 percent.Step 2: The contrapositive is: if yields do not drop by more than 50 percent, then crop protection products have been used. This contrapositive is logically equivalent to the original and is valid.Step 3: Option B essentially states that according to the NAAS, if crop yields per acre never drop by more than 50 percent, then crop protection products have been used. This matches the contrapositive and thus can be validly concluded.Step 4: Option D states that according to the NAAS, if crop yields per acre drop by more than 50 percent, then crop protection products have not been used. This is the converse of the original conditional and is not guaranteed to be true. Other factors could cause yields to drop even when products are used.Step 5: For aerial applicators, the passage states that in today's economy, all aircraft classified as aerial applicators also spread seed and apply fertilizer. Thus, if an aircraft is an aerial applicator, then it can spread seed and apply fertilizer.Step 6: Option A matches this structure and is a direct restatement, so it is valid. Option C is the contrapositive of that structure, also valid: if an aircraft cannot apply fertilizer, then it is not an aerial applicator.Step 7: Option E follows naturally from the definition: passenger only aircraft do not perform agricultural application tasks and so cannot be aerial applicators. This is consistent and can be accepted as a reasonable consequence.Step 8: Therefore, the only option that cannot be validly concluded is option D, which incorrectly assumes the converse of the NAAS conditional.

Verification / Alternative check:

Why Other Options Are Wrong (as answers to the question):

• Option A restates the given description of modern aerial applicators and is consistent with the passage.
• Option B reflects the contrapositive of the NAAS conditional and is a valid logical consequence.
• Option C expresses the contrapositive of the aerial applicator description and is valid.
• Option E is consistent with the idea that only aircraft performing agricultural application tasks are aerial applicators, so it does not contradict the passage.

Common Pitfalls:

• Confusing a conditional statement with its converse. The fact that no products implies large yield loss does not mean that large yield loss implies no products.
• Ignoring the contrapositive, which is always logically equivalent to the original conditional.
• Focusing only on the wording and not on the logical structure of the statements.

Final Answer:
The statement that cannot be validly concluded is: According to the NAAS, if crop yields per acre drop by more than 50 percent, then crop protection products have not been used to control insects, weeds, and diseases.