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

Only the right answer will accurately describe a flaw in the argument, which will be a reason the conclusion isn’t well supported.

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

this must be the conclusion

Food critic: [BACKGROUND]. [CONCLUSION], because [SUPPORT].

The author tried to get tricky on us. Did you catch it? The conclusion is about “good” seafood gumbo, but the support is about “the best”. That’s not the same thing. This author changed the subject, and the right answer will surely call that out.

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

(A) …testimony that is likely to be biased.

Not at all. What an argument “relies upon” is it’s support, but the “testimony” was in the background info.

(B) …if one of its ingredients lacks that quality

This is inaccurate. The quality of the okra is “fresh”, which isn’t the quality of the gumbo. Also, that’s all stated explicitly in the conclusion, so “illicitly presumes” doesn’t work either.

(C) …a sufficient condition for good seafood gumbo

The first part about the “necessary condition” maps to “the best seafood gumbo requires”, but this part doesn’t map to anything. The author never said fresh okra or anything else was “sufficient” for good gumbo.

(D) …a necessary ingredient of the best…is also a necessary ingredient of good…

Boom! This is the only answer that calls the author out for changing the wording without explaining it.

(E) …on some days Chris’s might be serving seafood gumbo made with fresh okra

What happens “on some days” doesn’t directly relate to whether folks can “count on getting good seafood gumbo”. This doesn’t map to the passage, and I’m glad we’re done here cuz this one made me hungry.

(D) is the correct answer.

Common pattern/s in this question: Even if it’s just one word, that can be good enough to signal the author changed the subject, which means the support doesn’t really back up the conclusion. And right answers will always call that out.