There is nothing wrong with answer A.

B implies that lake Baikal 'has rivers that drain'. Baikal doesn't actually have rivers. Meaning error.

C. The 'it' after the 2nd comma is incorrect as it breaks the flow of the sentence. The sentence core in C is: "Lake Baikal, with more rivers draining, it holds..."

D begins with 'While'. This implies a contrast that is non-existent in the intended meaning.

E fails to make the intended comparison. The author intends to say that Baikal holds more than all the other lakes. It is the quantity held or the extent of the holding action that should be compared. Answer E simply states that Baikal is 'more than all the lakes'. This doesn't make sense. Baikal 'holds more' would be the correct comparison. Notice that answer A says "Baikal holds 20%, more than the lakes". That is the right comparison.

The correct answer is A.

There are other errors in these sentences. A fuller discussion is available at GMATPrep QID 2063. To create timed drills with similar questions, set topic='Modifiers and Parallelism, Comparison' and difficulty='700+' in the Drill Generator.

-Patrick

IMO A

B is out becuase of two isses.

1. It starts with 'WITH'. As per my knowledge if sentence starts with 'WITH' it is wrong. Please correct me if I am wrong.
2. 'that' is after comma. It is wrong. 'That' should not have comma before it.

C is out because of 'it' (See in red). 'It' does not make any sense

D. Wrong comparison. Water is compared with the combination. Also I don't think that D is a complete sentence

E. is very awkward

A is correct here

gmatruler wrote:More than 300 rivers drain into Siberia's Lake Baikal, which holds 20 percent of the world's fresh water, more than all the North American Great Lakes combined.

(A) More than 300 rivers drain into Siberia's Lake Baikal, which holds 20 percent of the world's fresh water, more than all the North American Great Lakes combined.

(B) With 20 percent of the world's fresh water, that is more than all the North American Great Lakes combined, Siberia's Lake Baikal has more than 300 rivers that drain into it.

(C) Siberia's Lake Baikal, with more than 300 rivers draining into it, it holds more of the world's fresh water than all that of the North American Great Lakes combined, 20 percent.

(D) While more than 300 rivers drain into it, Siberia's Lake Baikal holds 20 percent of the world's fresh water, which is more than all the North American Great Lakes combined.

(E) More than all the North American Great Lakes combined, Siberia's Lake Baikal, with more than 300 rivers draining into it, holds 20 percent of the world's fresh water.