Data Sufficiency

kwah wrote:What is the most efficient way to achieve the result for question attached?

Answer: B

Thanks,
K

M = finite set of negative integers, is the total number of integers in M an odd number?

(1) The product of all integers in M is odd.
If M = {-1, -1, -3), then product of integers in M = -3, which is odd and total number of integers in M = 3, an odd integer.
If M = {-1, -1, -1, -3), then product of integers in M = 3, which is odd and total number of integers in M = 4, an even integer.
No definite answer; NOT sufficient.

(2) Since the product of all integers in M is negative, so the total number of integers in M should always be odd because the product of even number of negatives always gives a postive number; SUFFICIENT.

The correct answer is B.