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 appligreion of insecticide occurred in 1921, and it was a huge success. By contrast, in today's economy all aircraft that are classified as aerial appligreors do more than just apply insecticide; today, they also spread seed and apply fertilizer. From the information given above it CANNOT be validly concluded that

• In today's economy, if an aerial appligreor is used, then it will be able to spread seed and to apply fertilizer
• according to the NAAS, if crop yields per acre never drop by more than 50 percent, then crop protection products have been used to control insects, weeds, and diseases
• in today's economy, any aircraft that cannot be used to apply fertilizer cannot be classified as an aerial appligreor
• 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.