Sentence Correction

Presenters at the seminar, one who is blind, will demonstrate adaptive equipment that allows visually impaired people to use computers.

(A) one who

(B) one of them who

(C) and one of them who

(D) one of whom

(E) one of which

I have looked at a lot of forums but none say why B is not better than D, or rather what is wrong in B, Pls explain

Please comment.
OA is D

Option B may not be grammatically wrong. But option D is concise than Option B and hence wins. Remember the rule that short is sweet(and correct) on GMAT when there are multiple grammatically correct options.

B is not correct. This example question tests your knowledge of who and whom and when to use them. Here is the rule:

Who is always the subject of a sentence, i.e. Who let the dogs out?
Whom is always the object of the sentence, i.e. Mary did not know to whom to send the invitation

Here is another way to explain it that is cool and that I found on a
grammar website:

Rule Use the he/him method to decide which word is correct.
he = who
him = whom
Examples Who/Whom wrote the letter?
He wrote the letter. Therefore, who is correct.
For who/whom should I vote?
Should I vote for him? Therefore, whom is correct.
We all know who/whom pulled that prank.
This sentence contains two clauses: We all know and who/whom pulled that prank. We are interested in the second clause because it contains the who/whom. He pulled that prank. Therefore, who is correct.
(Are you starting to sound like a hooting owl yet?)
We want to know on who/whom the prank was pulled.
This sentence contains two clauses: We want to know and the prank was pulled on who/whom. Again, we are interested in the second clause because it contains the who/whom. The prank was pulled on him. Therefore, whom is correct.

Danielle

Thanks for the explanation It shows I am begining to forget things

No problem -- English has waaaay too many rules, idioms, colloquialisms, and exceptions to remember them all!

Danielle wrote:B is not correct. This example question tests your knowledge of who and whom and when to use them. Here is the rule:

Who is always the subject of a sentence, i.e. Who let the dogs out?
Whom is always the object of the sentence, i.e. Mary did not know to whom to send the invitation

Here is another way to explain it that is cool and that I found on a
grammar website:

Rule Use the he/him method to decide which word is correct.
he = who
him = whom
Examples Who/Whom wrote the letter?
He wrote the letter. Therefore, who is correct.
For who/whom should I vote?
Should I vote for him? Therefore, whom is correct.
We all know who/whom pulled that prank.
This sentence contains two clauses: We all know and who/whom pulled that prank. We are interested in the second clause because it contains the who/whom. He pulled that prank. Therefore, who is correct.
(Are you starting to sound like a hooting owl yet?)
We want to know on who/whom the prank was pulled.
This sentence contains two clauses: We want to know and the prank was pulled on who/whom. Again, we are interested in the second clause because it contains the who/whom. The prank was pulled on him. Therefore, whom is correct.

Thanks for these rules, I did encounter these rules earlier, but I tried framing a question on the sentence to see if he/him would be suitable to apply and thereby choose the correct answer choice. But I could not frame a question out of it to choose he/him. Can you help me frame a question on the sentence, and show me how you apply he/him to the sentence.

Well, this is one is not so simple because it has the idiom 'one of'. In this case instead of he/him, you can use they/them. It's the same thing -- it will help you chose whether it is object of subject.

Presenters, one of _____ is blind. (they/them?)

Presenters, one of them is blind. Therefore use whom.

No trick works every time, but the he/him thing does work in a lot of situations. If you spend to much time trying to use this method, I'd recommend discarding it and finding another.

Danielle