6. Which function has a horizontal asymptote of y = 3?

a. f (x) = 3 (2x)

b. f (x) = 2 (4) x-3

c. f (x) = 2 (3x)

d. f (x) = 2 (4x) + 3

D is the answer f (x) = 2 (4^x) + 3

All of those answer choices are linear equations when simplified which don't have asymptotes I believe unless they are in a piece-wise function.

For confirmation, graph them either manually or digitally on a site like Desmos. They are all lines that go on infinitely.