Answer: D, neither A nor B
Step-by-step explanation: In a function, the x (the input) cannot repeat in the given set of ordered pairs. In Set A, 2 repeats in the third and fourth ordered pairs. In Set B, 9 repeats in the third and fourth ordered pairs as well.
I would like to help but, I need more background information.
In the standard form of the equation
![\\ \ f(t)=Acos[b(t\pm c)]+k\\ \\](https://tex.z-dn.net/?f=%20%5C%5C%20%5C%20f%28t%29%3DAcos%5Bb%28t%5Cpm%20c%29%5D%2Bk%5C%5C%20%5C%5C%20)
The middle line =k
For our given problem
f(t) = 40cos (80t + 20)
On comparison we get k=0
Hence middle line=0