K={a,b,c,.............}
K is set of numbers.
rule 1: if x is present, -x is also present.
Thus if -1 is in K, we have 1 also. if we have 2, we have -2 also...
rule 2: if 2,3 are present: 6 is also present. And now as 2 and 6 are present, 12 should be present and similarly 24 should be present and so on it will continue.

12???
a) 2 is in K. thus -2 is also there and thus -4 is also there (rule 2) and thus 4 is there and so on..
by this we can get any power of 2. but we don't know whether 3 is there or not
Insufficient

b) 3 is in K. With this we can get any power of 3, but again absence of 2 means we can't say whether 12 is there or nor.

a&b) 2,3 means 6 is there and that means 12 is there
IMO C

We have to use the 2 rules to generate a set of elements and conclude whether 12 is present in the set or not

Statement 1 (Uses both rules)
K = {2,-2,-4,4,-16,...}. From this we can see that 12 is not present in the set. Sufficient

Statement 2 (Uses both rules)
K = {3,-3,-9,9,81,...}. Sufficient

I agree its a different type of ques....I also guessed C

yup C

IMO: D

Proceeded with the same solution as that of sl750. Please provide OA.

Thanks.