The correct answer is A. Refinement.
Monotony is the state of being dull and uninteresting, while variety is the state of being interesting and full of different things. Crudeness is the state of being rough and unrefined, while refinement is the state of being smooth and polished. Therefore, the pair of words “crudeness : refinement” has the same relationship as the original pair of words “monotony : variety.”
Option B, “raw,” is not the correct answer because rawness is not the opposite of refinement. Rawness is the state of being uncooked or unprocessed, while refinement is the state of being cooked or processed.
Option C, “sobriety,” is not the correct answer because sobriety is not the opposite of crudeness. Sobriety is the state of being serious and not drunk, while crudeness is the state of being rough and unrefined.
Option D, “simplicity,” is not the correct answer because simplicity is not the opposite of crudeness. Simplicity is the state of being easy to understand or do, while crudeness is the state of being rough and unrefined.