Answer:
D
Step-by-step explanation:
A relation is a set of related points. A function is a set of related points where no inputs repeat.
A. {(1, 2), (2, 3), (3, 2), (2, 1)}
This repeats (2,3) and (2,1). Not a function.
B. {(4, 2), (3, 3), (2, 4), (3, 2)}
This repeats (3,3) and (3,2). Not a function.
C. {(1, −1), (−2, 2), (−1, 2), (1, −2)}
This repeats (1,-1) and (1,-2). Not a function.
D. {(1, 4), (2, 3), (3, 2), (4, 1)}
This doe NOT repeat. Function.
