Math
posted by Keyaria .
In which of the following sets of points is y a function of x? A= {(2, 2), (4, 6), (5, 3), (5, 1)} B= {(2, 2), (3, 4), (4, 4), (5, 4)} C= {(1, 4), (2, 3), (4, 4), (4, 1)} D= {(1, 4), (1, 5), (2, 6), (3, 5)}

recall that if y=f(x) is a function, each x value must correspond to a single y value. No two distinct points may contain the same x value.
A fails: (5,3) and (5,1)
B works  distinct x values
C fails: (4,4) and (4,1)
D fails: (1,4) and (1,5)