When you enumerate you need to put comas between all the items except the ones which are connected by "and" : as A is not correct as it does not have comas, and B is incorrect as it has comas where "and" is.
now, in a way both C and D are correct, but C is the usual accepted version, and D is an example of "Oxford coma" (where the coma is optional, to remain on the safe side, choose C).
We may actually need the passage.
C is the correct answer, because, if you say that the narration is told in the third person, 'he/she' will be used. And if the narrator is omniscient, that means that he knows everything, what the characters are thinking/feeling.
