I remember this from fifth grade. We were learning like the kids at Ron Clark Academy, its Reducing Information!
The right answer is "A. The clergy "
You should be referring to the quote from "The Canterbury Tales" where the word gold is used to represent the clergy in all its purity that leaves it in such a high standard that nothing can reach it, just as gold can not be attained by rust.
I would say no because a simile is having something referred to something else for example as brace as a lion or crazy like a fox.
