keepsmilinyaar wrote:19. According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, that should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

(A) that should the present rate of buildup continue, the global concentration of this poison
(B) should the present rate of buildup continue, the global concentration of this poison
(C) should the present rate of buildup be continued, the global concentration of this poison
(D) the global concentration of this poison, were the present rate of buildup continue,
(E) that the global concentration of this poison, if the present rate of buildup did continue,


Doubt: Why cannot the answer be "B".

Correct Answer is "A"
Source: Test Code 42 GMAT Test Paper

"so rapidly ..." needs a "that" for correct construction. That leaves us
choice A and E.

E has incorrect "if ... did continue"

Hence A

19. According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, that should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

(A) that should the present rate of buildup continue, the global concentration of this poison
(B) should the present rate of buildup continue, the global concentration of this poison
(C) should the present rate of buildup be continued, the global concentration of this poison
(D) the global concentration of this poison, were the present rate of buildup continue,
(E) that the global concentration of this poison, if the present rate of buildup did continue

the use of the word "that" in the correct answer choice is indispensable...Hence this is limited to choices A&E

E is confusing and hence A makes perfect sense

keepsmilinyaar wrote:19. According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, that should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

(A) that should the present rate of buildup continue, the global concentration of this poison
(B) should the present rate of buildup continue, the global concentration of this poison
(C) should the present rate of buildup be continued, the global concentration of this poison
(D) the global concentration of this poison, were the present rate of buildup continue,
(E) that the global concentration of this poison, if the present rate of buildup did continue,


Doubt: Why cannot the answer be "B".

Correct Answer is "A"
Source: Test Code 42 GMAT Test Paper

Carefully re-read the whole sentence without the term "that" and notice that you'll come across a sentence fragment.

According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

A. According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, that should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

B. According to some experts, carbon dioxide is accumulating in the atmosphere so rapidly, largely because of the burning of fossil fuels, should the present rate of buildup continue, the global concentration of this poison will double by the end of the next century.

Hope you get why that is necessary