Sentence Correction

Doctors still know little about how the Listeria bacterium is spread and why the diseases it causes, listerisosis, afflicts some poeple in a contaminated area though it spares many others.

A.
B. where it spares
C. despite sparing
D. when sparing
E. while sparing

[spoiler]OA: E. I confused between A and E. Can anyone throw some light into this?[/spoiler]

limestone wrote:Doctors still know little about how the Listeria bacterium is spread and why the diseases it causes, listerisosis, afflicts some poeple in a contaminated area though it spares many others.

A.
B. where it spares
C. despite sparing
D. when sparing
E. while sparing

[spoiler]OA: E. I confused between A and E. Can anyone throw some light into this?[/spoiler]

Though, although and even though are used to show a contrast between two clauses.
e.g.- Though he loves doughnuts, he has given them up for his diet.

Notice how 'though' shows a situation which is contrary to the main clause to express opposition.

On the other hand - 'while' show clauses in direct opposition to each other.

e.g. - Mary is rich, while I am poor.

Hence E the usage of while is correct,

IMO E

Thevoid has mentioned about the usage of other preposition. "Despite" is used with the phrase and also shows contrast in the action.

"While" with "+ing" is normally used to show two actions or events occuring at the same time. It is true for both present and past tenses. eg. He arrived while I was taking my dinner.

can some expert explain this? It is an anomaly for a non-native speaker.

What is the source of this question - if something authentic - i would also like to have expert views on this question.

The source is SC1000, Q249.