Which relation is a function?

a. (35)

b. (35)

c. (112)

d. (11)

C

Step-by-step explanation:

Look for the case in which every input is unique (no repetitions).

A does not qualify, as 3 appears as an input twice.

B does not qualify, for the same reason

C qualifies (is a function), because all the inputs {1, 2, 3, 4} are unique.

D does not qualify (see A, above).

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50