Question

Which of these descriptions best defines the term "metaphysical conceit"?

Answer 1

The metaphysical conceit commonly use as a literary device is the comparison between the spiritual aspect of a person and a physical thing in the world, it can be interpreted as extended metaphor, taking the concept into account we can say that the “metaphysical conceit” is unusual comparisons to describe commonplace things, The answer is C.

Answer 2

My guess is 
unusual comparisons to describe commonplace things 
A conceit is an inflated idea, so to write as if ordinary things have some great metaphysical significance, where really there is no connection, would be a conceit.