1 alone is not sufficent
2 alone says they ether both positive or both negative

lets continue with 2
in the case they are both negative:
x<y

lets take x=-4 , y= -3.5

if we put it on the (1) we get x=0.5+y --> -4 = 0.5 - 3.5 --> -4 = -3

so it can't be made.

if both positive (1) is solve able

hence they are both positive and (c) is right

2(x-y) = 1
==> x-y = 1/2

Not sufficient.
x Positive y positive Ex 3/4 , 1/4
x Positive y negative Ex 1/4 , -1/4
x negative y negative Ex -1/4 , -3/4

x/y > 1 2 alone is not sufficient.

Consider 1 and 2.

x/y > 1 only when x and y are positive.

C is the Answer.

Thanks
raama

This one was tough for me. anyone has any idea what level this question stand?

anyway, I got it now. thank you