The choices are the below that can be found elsewhere:
a. { 1, 2, 4 }
b. { 0, 3, 5, 8 }
c. { 0, 1, 2, 3, 4, 5, 8 }
d. { ( 0, 2 ), ( 3, 1 ), ( 5, 2 ), ( 8, 4 ) }
The answer is B because the domain is just the X-values of the ordered pairs and you cant repeat them.
