The climax of a story is what the story revolves around, or the problem the character(s) is facing.
I’m assuming the answer is D
The mood (or tone) of the prologue is considered as sombre, dark, macabre... since from the start we're being told that this story is going to be a story of love, death and loss.
The correct answer is B, object of a preposition. In this sentence, the noun clause is 'what you said', and it comes directly after 'about', which is a preposition. This makes it the object of the preposition 'about'.
The answer is d: hope that helped!