[B] looks like the best choice to me. It took me
01:20 mins.
Especially in the early months, farmers may need to find resourceful ways, such as planting a diversity of crops or feeding the soil additional nutrients,
that ensure their harvests are large and more consistent than they would be otherwise.
A) that ensure their harvests are largeThat seems to modify additional nutrients.
B) to ensure their harvests are largerFirst part of the sentence presents a plan to be undertaken by the farmers whose intention is made clear by "to ensure their harvests ..". This seems like the logical continuation of the sentence.
C) thus ensuring their harvests are largercomma + ensuring is an action modifier, it is incorrectly showing the result of the previous action. The action has not taken place yet, so the usage of verb-ing modifier to depict the result of the preceding action is incorrect.
D) so that the harvests are largerThis option has got me a bit perplexed. "So that" is a description of WHY something is to be done.
Especially in the early months, farmers may need to find resourceful ways
, such as planting a diversity of crops or feeding the soil additional nutrients, so that the harvests are larger and more consistent than they would be otherwise.
But, meaning wise, this sounds off to me. It presents some kind of certainty to the desired event if the aforementioned steps are taken. And between B and D, I will mark B.
E) of ensuring their harvests are large larger should be used instead of large to be consistent with "more than".