The correct answer is B. frame narrative.
The narrator, Lockwood, starts off by recounting in 1st person a strange thing that happened to him in his landlord Heathcliff's home Wuthering Heights. Then, he asks Nelly Dean, his housekeeper, about Heathcliff and the uncanny mansion, and she tells him the whole story - and that is the second frame (the story within another story).
