B is the best answer. It gives the reader the context of the quote by stating the speaker and what is happening. It also has the quote which is more credible than just a word or two pulled out. Since it's just introducing this information, it also allows the writer of the essay to expand the idea with further explanation.
Answer:
When was the last time you set aside a few hours to help someone else? C
Explanation:
The answer is B) it creates a disharmony that suggests strife in the ample nation.