D is correct here. The pronouns "them" and "they" are technically ambiguous in all choices, but since that is a problem in all 5 options, we can ignore it here and instead focus on other issues. Parallelism between "raising" and the other item with which it's listed is necessary. Therefore, eliminate B and E, which use "cut" instead of "cutting." The intended meaning of the sentence is that suppliers are growing fish twice as fast as those fish would grow naturally, so again for the sake of parallelism, this time in a comparison, we eliminate A (which compares "growing fish" to "growth rate," i.e., a verb and a noun) and C (which changes the meaning by not specifying that it's the normal growth rate of the fish to which the suppliers' rate is being compared). D establishes parallelism in both issues, and is therefore correct.

To meet the rising marketing demand for fish and seafood, suppliers are growing fish twice as fast as their natural growth rate, cutting their feed allotment by nearly half and raising them on special diets.

A. their natural growth rate, cutting their feed allotment

B. their natural growth rate, their feed allotment cut

C. growing them naturally, cutting their feed allotment

D. they grow naturally, cutting their feed allotment

E. they grow naturally, with their feed allotment cut

Some thoughts:

1. Clause + As fast as +Clause.

Clause should be compared with another clause.

Example:
I am as fast as he (is).

=> From this rule we can eliminate A, B, and C since these options does not have clause after " as fast as".

2. Comma + Verbing:

We know that "Comma+verb+ing" should modify the "noun+verb" of the previous clause.
=> This also eliminates A and C.

3. We must see the non-underlined portion of the sentence:

The non-underlined portion of this sentence has "xx and raising them..."

Cutting and raising are parallel in option D. The option E is awkward.

My answer on this one is D.

=> Experts, please comment on the explanation.

thanks andrea for your response

To meet the rising marketing demand for fish and seafood, suppliers are growing fish twice as fast as their natural growth rate, cutting their feed allotment by nearly half and raising them on special diets.

A. their natural growth rate, cutting their feed allotment

B. their natural growth rate, their feed allotment cut

C. growing them naturally, cutting their feed allotment

D. they grow naturally, cutting their feed allotment

E. they grow naturally, with their feed allotment cut


IMO - D also , fish grow naturally rathar than rate . elimintates a,b,c
leaving d and e . D is more concise and has the right meaning

This is a comparison, as indicated by "twice as fast as..." The items compared must be parallel: "suppliers are doing something" should be matched with "twice as fast as + another verb-subject pair". Because the first part is a clause, the 2nd must also be a clause.

We can use this to eliminate everything but D and E. The distinction between the two is how the last part is introduced; to modify an entire clause, the GMAT tends to like "-ing" introduced modifiers. D is correct.

To better understand, have a look at a detailed solution: This is GMATPrep question 2411

If you have trouble with this type of question, use the Solutions Engine to identify and study similar questions from GMATPrep

-Patrick

gmat_perfect wrote:To meet the rising marketing demand for fish and seafood, suppliers are growing fish twice as fast as their natural growth rate, cutting their feed allotment by nearly half and raising them on special diets.

A. their natural growth rate, cutting their feed allotment

B. their natural growth rate, their feed allotment cut

C. growing them naturally, cutting their feed allotment

D. they grow naturally, cutting their feed allotment

E. they grow naturally, with their feed allotment cut

Some thoughts:

1. Clause + As fast as +Clause.

Clause should be compared with another clause.

Example:
I am as fast as he (is).

=> From this rule we can eliminate A, B, and C since these options does not have clause after " as fast as".

2. Comma + Verbing:

We know that "Comma+verb+ing" should modify the "noun+verb" of the previous clause.
=> This also eliminates A and C.

3. We must see the non-underlined portion of the sentence:

The non-underlined portion of this sentence has "xx and raising them..."

Cutting and raising are parallel in option D. The option E is awkward.

My answer on this one is D.

=> Experts, please comment on the explanation.

@@GOOD CATCH MAN!!