Read the passage on crude mineral oil and answer the question: According to the passage, what is crude mineral oil?

Introduction / Context:
This reading comprehension question checks whether you understand the basic scientific description of crude mineral oil given in the passage. The passage defines crude oil not just by its appearance but also by its composition. Careful reading and the ability to distinguish between correct and partially correct statements are essential skills being tested here.

Given Data / Assumptions:

• The passage states: "It is a complex mixture of many different substances, each with its own individual qualities."
• The context further explains that most of these substances are hydrocarbons and that similar hydrocarbons appear as bitumen, asphalt, and natural gas.
• Options present different characterisations of crude oil, some of which are incomplete or incorrect.
• We assume the reader has the full passage from the exam question in front of them.

Concept / Approach:
The key idea is that crude mineral oil is not a simple, pure substance but a mixture containing many components. The passage emphasises "complex mixture" and "many different substances". The correct option must capture both elements. Some distractors mention related materials like natural gas or bitumen, but they do not accurately define crude oil itself. Thus, the safest strategy is to match the option as closely as possible to the wording of the passage.

Step-by-Step Solution:
Step 1: Locate the definition sentence in the passage: "It is a complex mixture of many different substances, each with its own individual qualities." Step 2: Extract the essential points: complex, mixture, many different substances. Step 3: Examine option A: "Complex mixture of many different substances." This matches the key words almost exactly. Step 4: Examine option B: "Simple mixture of natural gas." This contradicts the passage, which says "complex" and refers to hydrocarbons in various forms, not just natural gas. Step 5: Examine option C: "Plain white oil." The passage mentions a thick brown or black liquid, so "plain white oil" is wrong. Step 6: Examine option D: "It is bitumen." The passage says similar hydrocarbons are found in other forms such as bitumen, but it does not say crude oil itself is bitumen.

Verification / Alternative check:
Re-read the section that talks about hydrocarbons. The passage states that crude oil consists mostly of hydrocarbons and that these hydrocarbons are also found in other forms like bitumen, asphalt, and natural gas. Therefore, crude oil is a mixture of such substances, not merely natural gas or bitumen alone. Option A is the only one that agrees completely with this explanation from the passage, confirming it as the correct answer.

Why Other Options Are Wrong:

• Simple mixture of natural gas: The passage emphasises "complex mixture" and mentions natural gas only as another form in which similar hydrocarbons occur, not as the entire substance.
• Plain white oil: This contradicts the described appearance ("thick brown or black liquid"). The phrase "plain white" is nowhere in the passage.
• It is bitumen: Bitumen is given as an example of another form of hydrocarbons, not a definition of crude oil. Equating crude oil with bitumen is incorrect.

Common Pitfalls:
Some candidates may focus only on the words "bitumen" or "natural gas" and assume that crude oil must be one of those. Others ignore the adjective "complex" and mistakenly choose an option with "simple". To avoid such traps, always pay attention to qualifiers like "complex", "many", and "different". These words can completely change the meaning of the sentence, and exam setters use them to differentiate right and wrong options.

Final Answer:
According to the passage, crude mineral oil is a complex mixture of many different substances.