Answer:
It's A.
Step-by-step explanation:
an = 4.2^n
When n = 1, a1 = 4 . 2 = 8.
When n = 2, a2 = 4 . 2^2 = 16
When n = 3, a3 = 4 . 2^3 = 32
and a4 = 64.
