Answer:
(c) y = 3^x
Step-by-step explanation:
A function is described as exponential if the independent variable is found in the exponent.
y = x^(1/2) . . . a square root function, not exponential
y = 2x^3 . . . . a cubic (polynomial) function, not exponential
y = 3^x . . . . . an exponential function