Hi everyone, The issue with answer option E is that although the author says "progress is the secret message of Luminism", the author is not concerned with popularity. E says "the most popular works of art at a given time are devoted to furthering economic or social progress", which is outside the scope of what we're discussing since the author isn't talking about popular works in general, rather just Luminist works.
This is a tricky question, and we might have to reach D via process of elimination. A, B, and C, aren't really supported, and once we eliminate E, D is the only option left. However, to come up with positive support for D I think we would look at the end of P2 and the beginning of P3. The author talks about where Lane lives, says his house has a view of the harbor, and then discusses how he views the sea as a trade route for commercial activity and not a free or powerful element (probably influenced by the fact he lived on and frequently painted harbors). If the author didn't agree with D, that "knowing about the environment in which an artist lived can aid in an understanding of a work by that artist", then they wouldn't have bothered to talk about where Lane lived and connecting where he lived to his depictions of harbors.
