Does anyone know how to solve this
With the explanation please

Answer:
B)
Step-by-step explanation:
Try B)
f(a) = 12(1/3)^a
b = 12(1/3)^a
f(a + 1) = 12(1/3)^(a + 1)
b = 12(1/3)^a × (1/3)^1
b = (1/3)[12(1/3)^a]
b = (1/3)f(a)
f(a + 1) = (1/3)f(a)
Answer: B)