https://classic.7sage.com/lsat_explanations/lsat-49-section-4-question-16/

I have a question about PT49.S4.Q16. If this were a sufficient assumption question, can (D) be a correct answer?

(D) says "beautiful → best." "Most beautiful" are beautiful, so it would to be "Most beautiful → beautiful → best." (D) certainly fills the gap in the argument. But I think it's not necessary since we don't need all beautiful pieces to be the best to conclude that "beauty" and "truth" are different.

Argument Breakdown:

[[Main Argument]]

Premise: A [beauty = truth] → X [most realistic (R) → best (B)]

(Sentence 2: If there were no difference, then the most realistic pieces of art would be the best as well)

Premise: /X [most realistic (R) and not best (/B)]

(Sentence 3: But many of the most realistic artworks are not among the best)

————————————

Conclusion: /A (beauty =/= truth)　

(Sentence 1: There is a difference between beauty and truth)

[[Sub-argument]]

Premise: A [beauty = truth] → C [most realistic (R)→ most truthful]

(Sentence 2: since the most realistic pieces are the most truthful)

A [beauty = truth] → C2 [most realistic (R)→ most beautiful]

[[[[[GAP IN THE ARGUMENT]]]]]

——————

Conclusion: A [beauty = truth] → X [most realistic (R) → best (B)]

(Sentence 2: If there were no difference, then the most realistic pieces of art would be the best as well)

[[[[[GAP IN THE ARGUMENT]]]]]

C2 (= C) → X

most realistic (R)→ most beautiful → best (B)

[[Answer choices]]