When I did this question, E seemed to have 2 problems: 1. "are disinclined to" in D is better than "have disinclination to" in E 2. "admit their lack of skills" is unidiomatic. should be "admit TO their lack of skills" with regard to the "incomplete" comment, i think it's saying the sentence following "while" is incomplete. My understanding is that while means "whereas" and connects two complete parallel sentences. A comma also needed to connect two clauses. Any comments from NNs? Here are some example i can find in OG. Hope they help! OG 37 While some academicians believe that business ethics should be integrated into every business course, others say that students will take ethics seriously only if ... OG 69 Although she had signed a pledge of abstinence while being an adolescent, Frances Willard was 35 years old before she chose to become a temperance activist.
(A) while being an adolescent (B) while in adolescence (C) at the time of her being adolescent (D) as being in adolescence（E） (E) as an adolescent A and B are unidiomatic because the clause after "while" are incomplete OG 137 The Commerce Department announced that the economy grew during the second quarter at a 7.5 percent annual rate, while inflation eased when... (See a comma needed here) OG 134. Canadian scientists have calculated that every nine years a human being will be struck by a meteorite, while each year sixteen buildings can be expected to sustain damage from such objects. OG 231. Ms. Chambers is among the forecasters who predict that the rate of addition to arable lands will drop while those of loss rise. (A) those of loss rise (B) it rises for loss (C) those of losses rise (D) the rate of loss rises（D） (E) there are rises for the rate of loss from this question you can see that the 2 clauses that "while" connects have to be paralle. | 
