Answer:
Improving food storage facilities
Genetically modified crops are genetically engineered such that a desired trait is enhanced or reproduced to appear in every offspring. Genetically engineered corn has been engineered to resist pests and herbicides; thus, we have more yield and many people especially in the low class society can afford. A disadvantage, yet is still a debate, is that genetically engineered crops such as corn, has toxic effects to internal organs such as our liver, a vital internal organ.
But this rule rule is applicable only for double stranded DNA molecule. The possibility of Adenine=40% and Thymine=60% is only in single stranded DNA molecule. In the question, the DNA sample referred is a single stranded DNA. hope it helps :D