C is obvious ans here.

Either both of 'em have to be positive or negative at the same time to know the ans.

From 1 : x-y>-2

Here we can't find whether (x-y) is positive or negative.
x and ys sign can't be fixed.

From 2 : same as above.

Now combining both we can see both x and y are positive.

from 1:
We have x-y>-2
=>x>y-2

and from 2 : x-2y<-6
=>x<2y-6

so, 2y-6>y-2
=>y>4 and then we can get x is also positive.