IMO B.

1)
suppose there are 3 numbers on the list.

they can be 0, 5, 0 or they can be 0, 0, 0.

the product of any two combination will result in 0.

but each of the numbers do not always = 0.

2)
again suppose there 3 numbers on the list.

The only way the sum of any two combinations that will result in 0 is 0,0,0.

(B)

2)
again suppose there 3 numbers on the list.

The only way the sum of any two combinations that will result in 0 is 0,0,0.

(B)

How about consider numbers as : 0, -3,+3

so as per B) Sum = 0, but individually the numbers are not 0

There can be numerous combinations like this

gmat740 wrote:
How about consider numbers as : 0, -3,+3

so as per B) Sum = 0, but individually the numbers are not 0

There can be numerous combinations like this

The numbers you chose are not a valid set b/c if I pick any two numbers from your set and I choose -3 and 3:

the product of -3*3 = -9 which does not satisfy requirement 1.

from the same set if I chose (-3,3) for requirement 2, I get -3+3 = 0
but if I chose (0,3) I get 0+3 = 3 which does not satisfy requirement 2.

-hope this helps.