So you found a solution that satisfies the system of equations but it's not one of the ones listed?
Then I guess what you should instead do is,
plug each of your options into the system and see which one holds true.
(1,0) = (x,y)
y = -2x+5
y = 1/2x
0 = -2(1) + 5
0 = 1/2(1)
1/2 does not equal 0,
so we can see that (1,0) is NOT the option we're looking for.