It's so much nicer to have the full question -

There is no agreement at present on what function, if any, certain herbs like gingko bilboa have in slowing the deterioration or improving memory.

(A) in slowing the deterioration or improving
(B) in the improvement or slowing of the deterioration of
(C) in slowed or improved deterioration of
(D) in the improvement to or the slowing of the deterioration of
(E) in slowing the deterioration of or improving

Breaking down to A and E.

Between them, I would choose E. Since, in A the parallel structure is like

1.slowing the deterioration memory - "deterioration memory" is wrong !
2.improving memory

However, in E the parallel structure is

1.slowing the deterioration of memory
2.improving memory

Pls someone confirm this !

thestartupguy wrote:It's so much nicer to have the full question -

There is no agreement at present on what function, if any, certain herbs like gingko bilboa have in slowing the deterioration or improving memory.

(A) in slowing the deterioration or improving This is incorrect. slowing the deterioration of what?
(B) in the improvement or slowing of the deterioration of This is not parallel. This is incorrect.
(C) in slowed or improved deterioration of This is incorrect. We don't want to say "improved deterioration"!
(D) in the improvement to or the slowing of the deterioration of This is wordy and not parallel. This is incorrect.
(E) in slowing the deterioration of or improving This is parallel and concise. This is the correct answer.

B,C, and D can be eliminated for obvious reasons. Picking between A and E is a little bit trickier. We need to make sure the sentence makes sense. A is incorrect because if we got ride of "or improving" the sentence would say "...in slowing the deterioration memory". This is incomplete and we need the all important "of"

@thestartupguy --> Thank you very much for posting the entire question.

@hellother--> I'm sure you're trying to save yourself some time, but when you post incomplete questions it makes it very difficult for people to help you and for others to practice. The point of this site is to learn and help others. By posting an incomplete question and unclear post, you do neither. Next time please help yourself as well as others. Thanks.

Ok. From next time, I will post the full question. But the real reason I did not post the full question was that I did not have a doubt in the "actual" question. The 2 options that I have given are not the actual options that are given for the question. I had a seperate doubt. So is there a way I can post questions in which I have "seperate" doubts ?

hellother wrote:Ok. From next time, I will post the full question. But the real reason I did not post the full question was that I did not have a doubt in the "actual" question. The 2 options that I have given are not the actual options that are given for the question. I had a seperate doubt. So is there a way I can post questions in which I have "seperate" doubts ?

You should post the entire question. Then at the end, state what questions/doubt you have. Honestly, when I reread your original post I don't really understand what your questions are.