Clearly between C and E.
(C) whether the movie should be classified as a murder mysteryYes, I think this is the correct one. First person clearly states that it is a requirement of murder mysteries that viewers be given clues to solve the mysteries. This first person thinks that the movie is indeed a murder mystery.
Second person, on the other hand, states that the filmmaker wanted to keep the murder thing as a side thing and his primary focus was something else. Clearly, in the second person's opinion, the movie is not a murder mystery as murder is a side element in the story.
(E) whether the filmmaker wanted viewers to be able to solve the murderWrong in my opinion.
First person simply states what are pre-requisites of a murder mystery. She never talks or implies that filmmaker "wanted" the viewers to be able to solve the mystery. So she cannot disagree with the second person on this topic.
Second person, on other hand, clearly believes that filmmaker does not want to divert any attention to murder stuff, and that murder element is just a secondary thing.
I welcome any comments on my reasoning

Appreciate Kudos if it helps xD
Regards,
Saakhi