Taking on the pairing answers strategy,
[*]obscure - no true pair, disregard could be argued as "equivalent" but definitely not a great pair
[*]disregard
[*]comprehend
[*]disparage - a little too extreme, no pair
[*]ignore
[*]fathom

Going to the sentence, we learn that "Edna couldn't understand..." At first thought, it already looks like it is going to be related to "comprehension". We see (C) comprehend and (E) fathom looking promising. Reading the rest of the sentence to double-check, we see that Edna can't seem to understand why all these other museum-goers just "could pretend to ________ its meaning" when she thought it was so "opaque" - or hard to understand. This confirmed (C) and (E) as correct.

The sentence said that for Edna is it strange that people pretend to ..., when for Edna the message is opaque (this means that the message is difficult to understand). So the blank word has to mean something related with understand. Comprehend and fathom are good options.

Opaque meaning is not clear, we should identify the opposite of Opaque, which are Comprehend & Fathom

For edna it was opaque so others would have understood it so comprehend and fathom are the options