Write the function for the graph

Answer:
(D). f(x) = 3 · [tex](4)^{x}[/tex]
Step-by-step explanation:
The equation of an exponential function is
f(x) = y = [tex]a(b)^{x}[/tex]
For point (0, 3)
3 = a [tex](b)^{0}[/tex] ⇒ a = 3
For point (1, 12)
12 = 3 [tex](b)^{1}[/tex] ⇒ b = 4
f(x) = 3 · [tex](4)^{x}[/tex]