Answer is E. We have a nice explanation in the link below
http://www.gmatclub.com/phpbb/viewtopic ... +differing
Now, cutting the whole thing short. D& E are the closest contenders for the answer.
E is the final answer because E brings in the gerund 'differing' which is more appropriate in this situation than the past participle 'differed'.
My understand is very simple, action following the word 'determined' lives in the past, and action following the word 'differing' lives in the present.