1. Time yourself
2. Solve this seperately using all the rules and idioms you can think of. no, this is not a clue. Only guess at the last resort.
3. Explain your answer here, and tell us how you did on time.
Even though its per capita food supply hardly increased during two decades, stringent rationing and planned distribution have allowed the People's Republic of China to ensure nutritional levels of 2,000 calories per person per day for its population.
(A) Even though its per capita food supply hardly increased during
(B) Even though its per capita food supply has hardly increased in
(C) Despite its per capita food supply hardly increasing over
(D) Despite there being hardly any increase in its per capita food supply during
(E) Although there is hardly any increase in per capita food supply for
B is best. The referent of the opening modifying clause does not have to immediately follow the comma if it the relationship is clear and unambiguous from the context. B also properly uses the present perfect in both the subordinate and main clauses to show that while the food supply did not increase over time from the past until now, they have managed to increase nutritional levels over that same time from the past until now. D is simply a mess.