What role does the dialogue play in this excerpt from The Hound of the Baskervilles by Sir Arthur Conan Doyle? "Would it not be well in the first place to get rid of this Barrymore couple?"

"By no means. You could not make a greater mistake. If they are innocent it would be a cruel injustice, and if they are guilty we should be giving up all chance of bringing it home to them. No, no, we will preserve them upon our list of suspects. Then there is a groom at the Hall, if I remember right. There are two moorland farmers. There is our friend Dr. Mortimer, whom I believe to be entirely honest, and there is his wife, of whom we know nothing. There is this naturalist, Stapleton, and there is his sister, who is said to be a young lady of attractions. There is Mr. Frankland, of Lafter Hall, who is also an unknown factor, and there are one or two other neighbours. These are the folk who must be your very special study."

A.
It gives information about various characters.
B.
It advances the plot of the novel.
C.
It resolves a conflict.
D.
It develops the theme of the novel.