What is the domain of the function shown in the mapping?
a {x|x = -5, -3, 1, 2, 6}
b {yly = -9,-6, 0, 2, 4}
c {x| x = -9, -6, -5, -3, 0, 1, 2, 4, 6}
d {yl y = -9, -6, -5, -3, 0, 1, 2, 4, 6}