If n and p are integers...? HELP

[gmatpup]

If n and p are integers, is p>0?

A. n+1 > 0

B. np > 0

Answer is C

Please explain! Thanks so much

[Anurag@Gurome]

If n and p are integers, is p>0?

A. n+1 > 0
B. np > 0

Answer is C
Please explain! Thanks so much

(1) Nothing has been said about p, so p may or may not be > 0; NOT sufficient.

(2) np > 0
If n = -1, p = -1, then np = 1 > 0; here p < 0
If n = 1, p = 1, then np = 1 > 0; here p > 0
No definite answer; NOT sufficient.

Combining (1) and (2), n > -1 and np > 0
Since n is an integer n cannot be 0 since np > 0 so n has to be positive. If n is positive p has to be positive as np > 0; SUFFICIENT.

The correct answer is C.

[neelgandham]

If n and p are integers, is p>0?

A. n+1 > 0

n+1>0, Implies that the value of n > -1, since n is an integer, the value of n of n > 0
Insufficient!

B. np > 0

np>0 implies
n>0 and p>0 OR
n<0 and p<0
So the value of p can be any integer on the number line(except 0)
Insufficient!

From 1 and 2
n>0 and p>0 Hence sufficient! Answer C