Jamesk486 wrote:

if wxy<0, xyz>0, is z>0?

(1) w<0

(2) x>0

St1... (-)(-)=(+) and (-)(-)(-) = (-) and since wxy is negative so if w<0 then

either x and y are both +ve

or x and y are both -ve

but it doesn't give further information. St1 insuff.

St2... says that x is +ve and that suggest that

either both y and z are positive

or both y and z are negative

no further information. St2 insuff.

Combined: by combining both we knows that both x and y are positive and since xyz is positive then z has to be positive. Suff.

IMO answer is C