Hi abhasjha,

The correct answer is C. It is concise, shows correct modification, and shows correct parallelism. The other answers have errors; let's look at them in detail:

A. When working with overseas clients, an understanding of cultural norms is at least as important as grasping the pivotal business issues for the global manager.

"When working with overseas clients,....." is a descriptive phrase that describes "global managers." According to the modification rules, "global managers" should come next (right after that comma). Eliminate A.

B. When they work with overseas clients, understanding cultural norms is at least of equal importance to the global manager as grasping the pivotal business issues.

Answer B has the same error as A - an incorrect phrase after the comma. Eliminate B.

D. For global managers working with overseas clients, an understanding of cultural norms is at least as important to them as that they grasp the pivotal business issues.

The sentence in D is ambiguous. It describes two things that matter to global managers (an understanding of cultural norms, and grasping business issues). These two things have to be written in "parallel format" and use a two-part phrase. Clearly, "an understanding of cultural norms is at least as important to them as that they grasp" is not parallel. Eliminate D.

E. Global managers working with overseas clients find an understanding of cultural norms to be equally important as grasping the pivotal business issues

Answer E is not a proper two-part phrase. Eliminate E.

C. For global managers working with overseas clients, understanding cultural norms is at least as important as grasping the pivotal business issues

This answer has proper modification, is parallel, and is expressed as a two-part phrase. Answer C is correct!