[bThe expected drop in the price of cotton could
be a serious impact to agrarian nations and severely diminish the possibility to attain an economic growth rate above 10 percent. [/b]
(A) be a serious impact to agrarian nations and severely diminish the possibility to attain
meaning wise it says expected drop could be a serious impact to nations rather than directly saying expected drop could seriously impact agrarian nations or could have an impact on nations. Also expected drop could severely diminish the possibility to attain suggests as if there is an intention of expected drop to attain economic growth
(B) seriously impact on agrarian nations and severely impede the possibility to attain
preposition on after verb is not required as the as verb requires an object "agrarian nations" here
(C) seriously impact on agrarian nations and severely impede the possibility of attaining
preposition on after verb is not required as the as verb requires an object "agrarian nations" here
(D) have a serious impact on agrarian nations and severely diminish the possibility of attaining
meaning wise expected drop could have a serious impact makes sense
expected drop could severely diminish the possibility of attaining....
So this answer looks right
(E) have a serious impact on agrarian nations and severely impede the possibility to attain
meaning wise expected drop could have a serious impact makes sense
expected drop could severely diminish the possibility to attain this means expected drop has intention to attain an economic growth