This is a type of an inference/main point question "If all the statements above are true, then which of the following can be concluded". So the correct conclusion should be of "must-be-true" type, i.e. we can surely say that this will happen.
3 options are outright rejected: B,C,D
Now of A and E, for which can we be sure will happen?
That will be A, since for E we are not sure whether people need to conserve food. May be there government does for them.
Now to explain why A will surely happen, consider the following:-
Global Grain Price = 100
Price in Poor Country = 50
Price in Rich Country = 150 (in general, rich countries have more expensive items)
Case 1: Slight increase in global grain price
Global Grain Price = 100+50
Price in Poor Country = 50+50 = 100% rise from last year
Price in Rich Country = 150+50 = 33.33% rise from last year
Case 1: Sharp increase in global grain price
Global Grain Price = 100+100
Price in Poor Country = 50+100 = 200% rise from last year
Price in Rich Country = 150+100 = 66.67% rise from last year
Therefore, we can surely say that "Even consumer in rich country would have to pay significantly more as compared to previous year". ("even" is explained by that when prices rise slightly consumers in only poor countries pay significantly more than their previous year but not in rich countries. But when prices rise sharply, even the consumers in rich countries pay significantly more than what they paid in the previous year).
Hope this helps.