PreCalculus
posted by Peter .
Which sets of ordered pairs represent functions from A to B? Explain.
A = {a, b, c} and B = {0, 1, 2, 3}
A. {(a, 1), (c, 2), (c, 3), (b, 3)}
B. {(a, 1), (b, 2), (c, 3)}
C. {(1, a), (0, a), (2, c), (3, b)}
D. {(c, 0), (b, 0), (a, 3)}
I narrowed it down to either B or C, but I'm not sure because they both don't use a letter or number twice as x. So I'm not sure which one is a function.

to be a function, each member of A must map to a single member of B.
A is not a function: c>2 and c>3
B is
C is not, since it does not map A onto B
D is