Why not A

Pardon me! I meant why not B!

To clarify: the answer choice that reads "its use of elements from everyday life"

I also selected B, but after looking closer at the passage I realized that the author's talk of "its use of elements from everyday life" is attributed specifically to the artists themselves, and I do not see any language that indicates that the author has an opinion on this.

Hi Kristin, Good question! However, we’re being asked about what the author values most highly, not the muralist themselves. For both answer choices A and D: though the muralists may have been in agreement with these things, what the author values most highly about this moment in culture is its impact on artistic innovation. For answer choice B, the explanation is similar—it’s about what the author values most highly, and brilliant is something we are told was distinctive to Siqueiros. The following paragraph (paragraph two) introduces our author’s thesis (or main point), which he elaborates on further throughout the rest of the paragraphs. This is how we know the author values C most—because that is the author’s main point. Hope this helps! Andrea