Understanding the argument -
Plant scientists have been able to genetically engineer vegetable seeds to produce crops that are highly resistant to insect damage. Fact
Although these seeds currently cost more than conventional seeds, their cost is likely to decline. Opinion
Moreover, farmers planting them can use far less pesticide, and most consumers prefer vegetables grown with less pesticide; therefore, for crops for which these seeds can be developed, their use is likely to become the norm. - Supporting premise and conclusion.
We need to evaluate what? Evaluate that "The use of genetically engineered vegetables (GEVs) is likely to become a norm."
What can be some of the assumptions in this?
The taste of the GEVs is not drastically different, so people don't like them.
The yield is not bad.
The GEVs don't cause health issues to people who eat them.
Now, we need to know that the evaluation questions are based on assumptions with a difference, which is that we add a question mark. Since these are based on assumptions when doing a Yes/No analysis, one scenario will strengthen the conclusion, and the other will weaken.
Option Elimination -
(A) Whether plant scientists have developed insect-resistant seeds for every crop that is currently grown commercially. - "Every crop" doesn't matter as the argument clearly says, "Therefore,
for crops for which these seeds can be developed, their use is likely to become the norm." Out of scope.
(B) Whether farmers typically use agricultural pesticides in larger amounts than is necessary to prevent crop damage. - Doent matters for this scope, evaluating"The use of genetically engineered vegetables (GEVs) is likely to become a norm." Out of scope.
(C) Whether plants grown from the new genetically engineered seeds can be kept completely free of insect damage. - "Completely" is a distortion. The argument says that it is "highly resistant to insect damage" and not 100% resistant. Distortion.
(D) Whether seeds genetically engineered to produce insect-resistant crops generate significantly lower per acre crop yields than do currently used seeds. - Ok.
Say, yes, seeds genetically engineered to produce insect-resistant crops generate significantly lower per acre crop yields than currently used seeds - weakens the conclusion.
No, seeds genetically engineered to produce insect-resistant crops do not generate significantly lower per-acre crop yields than currently used seeds, which strengthens the conclusion.
(E) Whether most varieties of crops currently grown commercially have greater natural resistance to insect damage than did similar varieties in the past. - The comparison of current non-GEVs with past non-GEVs is out of scope.