Which of these systems is dependent?

A. x−y=2 and x+y=−2
B. x−y=2 and −2x+2y=−4
C. x−y=2 and 3x−3y=2
D. x−y=2 and −x−y=−2

The system that is dependent is A. x-y=2 and x+y=-2.