Are you sure that C is correct?
problem:
if x > y, is zx > yx ?
(1) z > 0
(2) y < 0
Let as look at zx > yx
We can deduct yx on both sides of an inequality zx - yx > 0,
we can further reshape it x(z - y) > 0
(1) z > 0
at this point we can plugin numbers
z=5 x=8, y=7
z(x - y) = 8(5-7) = -16
thus x(z - y) < 0
let us try other numbers
z=5, x=4, y=2
z(x - y) = 4(5 - 2) = 12
thus x(z - y) > 0
It is insufficient
(2) y < 0
now let us try to plugin numbers
z=5 x=-2, y=-3
z(x - y) = -2(5+3) = -16
thus x(z - y) < 0
let us try other numbers
z=3, x=1, y=-2
z(x - y) = 1(3+2) = 5
thus x(z - y) > 0
it is insufficient
According to me correct answer is E
hope it helps!
Best
