Which of the Following Specifies a One-To-One Function

Multiple Choice

Which of the following specifies a one-to-one function?

A) h = {(1,1) , (2,2) , (3,1) }
B) f = {(0,1) , (0,2) , (1,3) }
C) g = {(1,1) , (2,2) , (3,2) }
D) None of the above are one-to-one functions.