A compound subject is a sentence with two or more subjects. So the question is asking for a sentence that AGREES with its compound subject or two subjects which would be A. Because the ladybug AND spider whereas the others have OR.
Unreliable narrator refer to the narrator whose point of view has been seriously compromised
Usually, if in the beginning of the story the narrator admit that he's mentally ill or he's one of the character of the story could be used as a clue
hope this helps