Answer:
(C)y=0
Step-by-step explanation:
An exponential function of the form [tex]f(x) = a (b^x) + c[/tex] always has a horizontal asymptote at y = c.
Given our function [tex]y=4^x[/tex]
Comparing with the form, [tex]f(x) = a (b^x) + c[/tex], we observe that c=0.
Therefore, the exponential function has an asymptote at y=0.
The correct option is C.