Question

Identify the relation that is also a function. A. {(4, 2) (4, -3) (9, 3) (9, -3)} B. {(1, 0) (2, 3) (3, -1) (1, 5)} C. {(0, -1) (1, -2) (2, -3) (-1, 2)} D. {(5, 4) (5, 1) (5, 3) (0, 5)}

Can some one explain?? So i can do functions on my own ://

Answer 1

a relation is not a function if one value of x maps to more than one value of y.

So, which relation has unique 1st elements for all its pairs?