The difference between a monologue and a soliloquy is that in a soliloquy, the speaker is not addressing anyone. While a monologue may be addressed to someone. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help.
Elimination
short works should be in quotation marks but longer ones should be in italics
they should not be underlined
they should not have a period
it shold not be brief, you should not shorten a title since you didn't write the book.
answer is A
The answer is not A, because it is not clear enough. Who's we?
The answer is not B, the sentence is not clear about the building they are visiting.
The answer is not C, it's not clear about what building they are talking about.
So your answer is D.