The given function is

A . f(4) means we have to evaluate the function when x = 4.

Therefore, f(4) = 14.
B. f(x) = 50 means we have to evaluate the function when y = 50.-

Therefore, f(16) = 50.
C. f(-5) means we have to evaluate the function when x = -5.

Therefore, f(-5) = -13.
D. f(x) = -34.

Therefore f(-12) = -34.