Remember to always post your sources. This question is from GMAT Prep.

There are slight discrepancies between your text and the original. Here is the original:

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.

The intended meaning of the sentence is 1) 300 rivers drain into Lake Baikal, 2) it has 20% of the world's fresh water, and 3) that's more fresh water than the Great Lakes combined.

A) This conveys the intended meaning, without grammatical errors. Correct.

B) "That is more than..." is functioning as an independent clause in this sentence, making it a run-on sentence.

C) Without the prepositional phrase, this reads "Siberia's Lake Baikal... it holds." The "it" was unnecessary, as "Lake Baikal" was already the subject.

D) There is nothing grammatically correct with this one, but there is a meaning violation. The word "while" should create contrast between two ideas, but having "300 rivers drain into it" and holding "20 percent of earth's water" are not contrasting ideas.

E) The construction "more than X, Y does something" cannot be used here. We use it to express additional attributes: "more than a teacher, she is also a friend." It is nonsensical in this context.

The correct answer is A.