An adverb clause gives information about:

the verb, an adjective or another adverb

Explanation:

i think it may be b, i'm not exactly too sure on this. but b seems to make more sense.

jenkins wanted the narrator to write a ghost story for his magazine. he wanted the narrator to give the readers a story based on the supernatural. he wanted him to give the readers real 'horror' stories and not the type of live ghosts which he had presented in his earlier stories.