Question

Does the set of ordered pairs {(1, 4), (2, 7), (3, 4), (4, 11)} represent a function?
A. Yes, because there are no repeated input or output values.
B. No, because the input value of 3 should have a larger output.
C. No, because the output value of 4 is used more than once.
D. Yes, because each input value has only one output value.

Answer 1

D. Yes, because each input value has only one output value.

(Repeated outputs are allowed in a function; what's not allowed is an input mapping to more than one output.)