The sentence tests modifiers among other things; it begins with a description of rice (what has more protein than wheat?), so "rice" should start the underlined portion.

I go over each answer choice in detail in the full solution below (taken from the GMATFix App).



-Patrick

Can someone please explain what kind of a modifier is "In addition to having more protein than wheat does". I understand that this must be followed by "rice" in this case, but is this a general rule that all prepositional phrases must be followed with "what" they are modifying?

Can we generalize it this way?

iongmat wrote:Can someone please explain what kind of a modifier is "In addition to having more protein than wheat does". I understand that this must be followed by "rice" in this case, but is this a general rule that all prepositional phrases must be followed with "what" they are modifying?

Can we generalize it this way?

In addition to running for mayor...
Besides playing the clarinet...
Despite speaking four languages....

These introductory modifiers typically serve as ADVERBS, providing CONTEXT for the action in the following clause.
Even though their primary role is adverbial, these modifiers must satisfy one very important constraint:
The SUBJECT of the modified clause must be responsible for the VERBing action in the modifier.

In addition to HAVING more protein than wheat does, RICE has protein of higher quality than that in wheat.
Here, the introductory modifier (in addition to having more protein) provides context for the action in the modified clause (rice has protein of higher quality):
HOW does rice have protein of higher quality?
It has protein of higher quality IN ADDITION TO HAVING MORE PROTEIN THAN WHEAT DOES.
Note that the subject of the modified clause (rice) is responsible for the VERBing action in the modifier (having).
WHO or WHAT is responsible for HAVING MORE PROTEIN?
RICE is responsible for HAVING MORE PROTEIN.

Thanks Rich and Mitch. It is much clearer now.