distunguish from or between?

[thegmatbeater]

In his research paper, Dr. Frosch, medical director of the P.W.Clinic, distinguishes mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois.

a)mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois

b) between mood swings, which may be violent without being grounded in mental disease, and genuine manic depressive psychois

[Stuart@KaplanGMAT]

In his research paper, Dr. Frosch, medical director of the P.W.Clinic, distinguishes mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois.

a)mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois

b) between mood swings, which may be violent without being grounded in mental disease, and genuine manic depressive psychois

Both are idiomatically correct.

We can say either:

distinguishes A from B

or

distinguishes between A and B.

So, ignoring what's between the commas, we have:

a) distinguishes mood swings from genuine manic depressive psychois; and

b) distinguishes between mood swings and genuine manic depressive psychosis

both of which are just fine.

Accordingly, in this question it comes down to what's between the commas, specifically the extra "their" in the first choice, which hurts the parallelism of the sentence.

[thegmatbeater]

get it! thank you..

[beeparoo]

In his research paper, Dr. Frosch, medical director of the P.W.Clinic, distinguishes mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois.

a)mood swings, which may be violent without their being grounded in mental disease, from genuine manic depressive psychois

b) between mood swings, which may be violent without being grounded in mental disease, and genuine manic depressive psychois

Both are idiomatically correct.

We can say either:

distinguishes A from B

or

distinguishes between A and B.

So, ignoring what's between the commas, we have:

a) distinguishes mood swings from genuine manic depressive psychois; and

b) distinguishes between mood swings and genuine manic depressive psychosis

both of which are just fine.

Accordingly, in this question it comes down to what's between the commas, specifically the extra "their" in the first choice, which hurts the parallelism of the sentence.

After experiencing some difficulty spotting subtle parallelism problems, I have to ask: What areas of the part that lies "between the commas" are supposed to demonstrate parellelism?

Is it (1) be violent and (2) being grounded?

[Stuart@KaplanGMAT]

It's "their":

which may be violent without their being grounded in mental disease

.

[Fiver]

Accordingly, in this question it comes down to what's between the commas, specifically the extra "their" in the first choice, which hurts the parallelism of the sentence.

Hi Stuart, thanks for your comments.

I was wondering whether 'being' here plays the role of a gerund.
And if yes, won't we need some possessive form to preceed it?

Request you to please clarify.

Thanks in advance.