HG10 wrote:K is a set of numbers such that

i. if x is in K, then -x is in K, and
ii. if each of x and y is in K, then xy is in K.

Is 12 in K?

1. 2 is in K
2. 3 is in K

OA: C

Source: No. 70.,OG Quant Review, 2nd Edition

12 = 2*2*3 = (2)*(-2)*(-3)

For 12 to be there in K, we need two 2s and a 3.

Statement(1):
We have a 2 and a (-2) and thus a (-2)*(2) as well. But, we need 3 also. No information on that.
INSUFFICIENT

Statement(2):
We have a 3 and a (-3). But, we need a 2 also. No information on that.
INSUFFICIENT

Let's combine.
The simplest of all is (2)*(-2)*(-3) = 12
SUFFICIENT

[spoiler](C)[/spoiler] is the answer.

Thank you, Aneesh!