Read the sentence from Henry David Thoreau's Walden, and then answer the question.


"I know of no more encouraging fact than the unquestionable ability of man to elevate his life by a conscious endeavor."


Which BEST describes the meaning of the sentence?

A. Man improves his life when he is aware of what he is meant to do.

B. Time is often filled with man's attempts to find out the purpose of life.

C. Deliberate efforts to discover a professional life are often unsuccessful.

D. Man improves his quality of life when he follows the rules set forth by others.

(If answered quickly I will mark Brainliest.)