Answer:
I believe the correct answer is B) He uses a metaphor to compare an uncashed check to the promises of America.
Step-by-step explanation:
A metaphor is a figure of speech that describes one thing by referring to something else. Therefore, it uses words and phrases in their non-literal meaning. A check (cashed or uncashed) has a precise meaning of "a written order to a bank to pay the amount specified from funds on deposit" (according to TheFreeDictionary.com); when Luther uses it in this context, he refers to something entirely different - the promise of universal human rights. It's like a check that all Americans should be able to cash in. We can only infer this meaning by looking at the context.
Metaphors do function by comparing one thing to another. But unlike similes, they don't use prepositions such as "like" or "as".