Plug in until you get a false answer.
A (2,-1)
(2)-2(-1)=4
2+2=4
-2(2)+4(-1)=-8
-4-4=-8
B(4,0)
(4)-2(0)=4
4-0=4
-2(4)+4(0)=-8
-8+0=-8
C(0,2)
(0)-2(2)=4
0-4=4
-4=4
-2(0)+4(2)=-8
0+8=-8
8=-8
D(6,1)
(6)-2(1)=4
6-2=4
-2(6)+4(1)=-8
-12+4=-8
The correct answer is C because (0,2) makes the equation untrue.