A CT scan, used to capture images inside the body, differs from an MRI

Official Explanation

A CT scan, used to capture images inside the body, differs from an MRI, bounced radio waves off fat and water molecules in the body and then to a receiver in the machine that creates an image.

A. bounced radio waves off fat and water molecules in the body and then to a receiver in
B. bouncing radio waves off fat and water molecules in the body to a receiver of
C. radio waves being bounced off fat and water molecules in the body to a receiver in
D. which bounce radio waves off fat and water molecules in the body and then to a receiver within
E. which bounces radio waves off fat and water molecules in the body to a receiver in

After a quick glance over the options, we have 2 main areas we can focus on:
1. Their beginnings (Modifiers & Meaning)
2. Their endings (Punctuation & Meaning)

Let’s start off with #1 on our list. We need to determine what the purpose of the underlined phrase is to the whole sentence:

A CT scan, used to capture images inside the body, differs from an MRI, bounced radio waves off fat and water molecules in the body and then to a receiver in the machine that creates an image.

It appears that this sentence is doing two things:
1. Contrasting two machines (CT scan vs. MRI) = in blue
2. After introducing each machine, it explains what they do = in orange

We need to make sure the underlined modifier is clearly explains what an MRI does, and eliminate any that don’t accomplish this:

A. bounced radio waves off fat and water molecules in the body and then to a receiver in
(an MRI isn’t made out of radio waves, so this doesn’t really make sense)

B. bouncing radio waves off fat and water molecules in the body to a receiver of
(this suggests that the MRI does the action itself, which is also not logical)

C. radio waves being bounced off fat and water molecules in the body to a receiver in
(again, an MRI isn’t made of radio waves, it’s a machine that creates and bounces them around)

D. which bounce radio waves off fat and water molecules in the body and then to a receiver within
(much better indication of what an MRI does, which works well with the description of the CT scan earlier)

E. which bounces radio waves off fat and water molecules in the body to a receiver in
(much better indication of what an MRI does, which works well with the description of the CT scan earlier)

We can eliminate options A, B, and C because they create problematic issues with modifiers and the overall intended meaning of the sentence. Now that we have it narrowed down to only 2 options, let’s take a closer look at both to see which is the better choice:

D. which bounce radio waves off fat and water molecules in the body and then to a receiver within
This is INCORRECT for a couple reasons. First, the plural verb “bounce” doesn’t match up with the singular “MRI.” Second, the ending phrase is too wordy – option E says the same thing with far fewer words.

E. which bounces radio waves off fat and water molecules in the body to a receiver in
This is CORRECT! The verb “bounces” matches up perfectly with “MRI,” and the sentence is written using clear and concise language.

There you have it – option E is our winner!

Don’t study for the GMAT. Train for it.

EMPOWERgmatVerbal ,
Could you please help explain the following :

B. bouncing radio waves off fat and water molecules in the body to a receiver of
(this suggests that the MRI does the action itself, which is also not logical)
Isn't it the MRI machine that does the action . What am I missing here. Please help.
If MRI is meant as a technique here, then how 'which' is better.

D. which bounce radio waves off fat and water molecules in the body and then to a receiver within
(much better indication of what an MRI does, which works well with the description of the CT scan earlier)

Which works with the description of CT scan earlier, could you please explain this a bit. How it works with the CT scan description.

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May you please help on why ,bouncing cannot refer to city scan .

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