Which of the Following Is Not a Valid Partial Explanation

Which of the following is not a valid partial explanation for why the actor-observer effect occurs?

A) When we observe someone else's behaviour, we do not have access to their thoughts and feelings.
B) When we consider our own behaviour, we are motivated to maintain a positive self-image.
C) When we consider our own behaviour, we do not have access to our thoughts and feelings.
D) We do not know how strangers behave in particular situations.