To help counteract the adverse effects of trout stocking on the amphibian populations in certain mountain lakes, biologists are recommending
cutting back on trout stocking on the part of some states and even their being removed from some popular fishing lakes.
(A) cutting back on trout stocking on the part of some states and even their being removed -- recommending needs that
(B) cutting back on trout stocking on the part of some states and even that they remove them -- same as A
(C) that trout stocking be cut back in some states and they even remove the trout -- verb tense issue; Because the two actions are taken as similar/equivalent, they should be in the same form (e.g. "biologists are recommending x and even removing some trout...")
"Are recommending" is present-tense...it's going on now. "They even remove" is an indicative-tense, "that's just what happens" verb, so logically it doesn't make sense, either. The purpose of the sentence is to talk about current events happening in trout stocking.
(D) that some states cut back on trout stocking and even their being removed -- usage of being
(E) that some states cut back on trout stocking and even remove the trout - Correct
Answer E