Current data suggest that, although ------- states between fear and aggression exist, fear and aggression are as distinct physiologically as they are psychologically.
A) simultaneous
B) serious
C) exceptional
D) partial
E) transitional
The idea is to focus on the word although which indicates contrast and the word ‘distinct’ which is the focus of the contrast. So we want a word that is the opposite of distinct. That rules out options A,B and C. Between D and E, E makes more sense because of the word ‘between’ in the sentence. If something is between 2 states then it is transitioning. Hence the answer is E.