GoalStanford wrote:

I fell for the trap.C is correct.

S is a set of integers (not necessarily just positive integers).Question is "Is every multiple of 5 is in S?".

#1 misses negtive multiples (-5,-10...)

#2 misses positive multiples (5,10,...)

So,together covers all multiples.

That is the beauty of the DS questions.Small twist to a relatively easy question can differrentiate best people from the good.

Actually, I'm not sure negatives are considrered as multiples. I thought that (2) brought that info but then I changed my mind and thought that (2) actually brings 0 which (1) does not.

Also, when reading the question again my heart is going to D (even if i know it's not the answer).

(1) No --> sufficient

(2) No --> sufficient.