what is the domain of the function shown is the table
x y
(2,3)
(4,4)
(6,5)
(8,6)

A.{3,4,5,6}
B.{2,4,6,8}
C.{2,3,4,5,6,8}
D.(2,3), (4,4), (6,5),(8,6)