nitya34 wrote:

OE says

It's easiest to find examples that prove the other four choices wrong. For answers A, B, and C, choosing a=2 and b=4 makes the statements incorrect. For answer E, choosing a=4 and b=8 makes the statement false. Answer D is the only one that holds true always.

thx

Either the OE is wrong, or there's a word missing from the question. What's the source? D certainly must be true *if* a and b are *positive* even integers. The question (as posted) only says that they are 'non-zero', which means they could be negative. If a = 2, and b = -2, then a^b = 1/4, and is not an integer, so certainly is not even.

_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com