Which of the following is a geometric sequence?

a. 3, 7, 11, 15, 19

b. 4, 6, 10, 16, 26

c. 4, 16, 64, 256

Hello,

A: is an arithmetic sequence: f (n) = 3 + (n-1) * 4

B: is a Fibbonacci's sequence f (n+2) = f (n+1) + f (n), f (1) = 4, f (2) = 6

C: is a geometric sequence : first term = 4 ratio=4

f (n) = 4*4^ (n-1) = 4^n