Find the domain of the relation below.
(4,2).(-2,4), (0, 1), (1,5)
A. {4, -2, 1,5}
B. {2, 4, 1,5}
C. {4, 2, -2, 4, 0, 1, 1,5}
D. {4, -2, 0, 1}