a function has 1 input gives only one output
you cannot have
input 2 and get 4
then later
input 2 and get 6, that is not a function
basically x never repeats with a different y so
A. the -2 repeats with the 3 and 6
B. the 14 repeats with 1 and 2
C. no repeats
D. 8 repeats with 1 and -9
answer is C because the rest have some repeats
