A) "be a serious impact to agrarian nations and severely diminish the possibility to attain"
"impact" should be used with the preposition "on" and not "to". Also, "the possibility to attain" sounds incorrect. (eliminate)
(B) "seriously impact on agrarian nations and severely impede the possibility to attain"
Here, "impact" is incorrectly used as a verb with the preposition "on". I think, when "impact" is used as a verb, it does not take a preposition. (eliminate)
(C) "seriously impact on agrarian nations and severely impede the possibility of attaining"
Same issue with "impact" as in (B). When "impact" is used as a verb, it doesn't require the preposition "on". (eliminate)
(D) Option D: "have a serious impact on agrarian nations and severely diminish the possibility of attaining" is the best choice.
This option uses "have a serious impact on," correctly using "impact" as a noun with the appropriate preposition, and it also uses "the possibility of attaining", the correct construction after "possibility". Sentence construction and logic seems to be fine. (keep for now)
(E) "have a serious impact on agrarian nations and severely impede the possibility to attain"
Here, "the possibility to attain" is incorrect. It should be "the possibility of attaining". (keep, but can be eliminated)
I will go with option D.
Waiting for OA.