How will the right answer fit in terms of support and conclusion?

Only the right answer will support disagreeing with the conclusion.

Highlight the main conclusion in the passage, if there is one:

the risk is minimal.

Scientist: [BACKGROUND]. However, [CONCLUSION]. [SUPPORT]. Since [SUPPORT], [INTERMEDIATE CONCLUSION].

Map the wording of the answers to the wording of the passage:

(A) …have few advantages over plants that are not…

This is making a comparison that never comes up in the passage. The lack of “advantages” doesn’t map to a conclusion about “risk”. This doesn’t tell us anything about the risk, so it doesn’t impact the conclusion.

(B) …may be somewhat reduced…

If the risk can be reduced, that would align with the author’s conclusion about “minimal” risk. This is pretty vague and weakly worded anyway, but it doesn’t support disagreeing with the author in any case.

(C) Scientists have yet to determine…

Calling out unknowns could support disagreeing that risk is “minimal”, but this only says it’s “some plants and animals”. How many is “some”? Enough to make a difference in how much “risk” there is? We have no idea, so you’d have to add in your own assumption to connect this to disagreeing with the author. That means it’s the wrong answer.

(D) …known to be affected by the alteration of a single gene.

This is the only answer that maps to the author’s argument directly. If “a single gene” is enough to have an effect, then you might doubt the author’s argument about the change being “so slight” and therefore not “worrisome”. That’s enough to keep this answer in the running.

(E) …tend to be ill-informed…

Cool story, but how well informed people are has nothing to do with “the risk” of genetically engineered foods. The argument doesn’t rely on anyone being informed, so this doesn’t support disagreeing.

(D) is the correct answer.