!!! time sensitive please answer !!!

consider the sequence below. 3, 1, 1/3, 1/9

select the explicit function which defines the sequence

A. f(n) = 1/3 • 2^(n-1)

B. f(n) = 2 • (1/3)^(n-1)

C. f(n) = 3 • (1/3)^(n-1)

D. f(n) = 1/3 • 3^(n-1)