Option B is the correct answer because “to alleviate” means to make less severe or to decrease the effect of.
While the other three options mean to increase; as in,
Option A, enhance, means to intensify, increase, or further improve the quality, value, or extent of.
Option C, expand, means to become or make larger or more extensive.
Option D, to grown means to become larger or greater over a period of time; increase, hence the only different word is “alleviate”.