<span>Depending on which excerpt of the line you are indicating, William Cullen Bryant's "Thanatopsis" is a theme between a man and the natural world. It is a poem about death. It also talks about nature. It is believed that human beings come and go. On the other hand, nature is always there - the mountains, rivers, seas, forests.</span>
You cannot put any sort of endmark (period, question mark, or exclamation point) here because it is not a complete sentence. Complete sentences must have a subject and a predicate. You can tell there's not even a verb here, so this is just a fragment, and we would have to use a comma.
a. Very truly yours,
Answer:
B is correctly punctuated.
