. Does the table represent y as a function as x? 
x: 0,3,3,5
y: 2,1,-1,3
a. Yes, because every x-value has exactly one y-value. b. Yes, because y-value there is exactly one x-value. c. No, because one x-value has two y-values. d. No, because there is a 3 in the domain and a 3 in  the range.