NikhilThachil
Sorry but I couldn't understand how a) is the right answer?
Here's what the passage says.
Neither a rising standard of living nor balanced trade, by itself, establishes a country's ability to compete in the international marketplace. Both are required simultaneously ....So, two things are required for a country's ability to compete to be established: a rising standard of living and balanced trade.
Now, let's consider (A).
If the facts stated in the passage above are true, a proper test of a country's ability to be competitive is its ability to
(A) balance its trade while its standard of living risesWe see that (A) follows from what the passage says. After all, if "a rising standard of living" and "balanced trade" are "required" for establishing a country's ability to compete, then it follows that, if we want to "test" a country's ability to competitive, then we should consider its ability to do the two things "required" for establishing a country's ability to compete, "balance its trade while its standard of living rises," which are just what (A) mentions.