Data Sufficiency

help

1. The product of the set is odd.
All this tells us is that all of the numbers in the set are odd. It doesn't tell us anything about the number of integers in the set

ex:
(-1,-5,-3) = -15 (odd #'d set)
(-5,-3)= 15 (even #'d set)

Insufficient

2. The product of all the integers is odd
Because the entire set is negative and because an even number of negative numbers produces a postive number, the only way that the product would be odd is if there is an odd number of integers in the set.

Sufficient.

Hope that helps.

(1) is insufficient.
-3 * -3 = 9 (Even numbers)
-3 * -3 * -3 = -27 (Odd numbers)

(2) is sufficient

-a * -b * -c = negative integer
-a * -b = positive integer

Hence B.