The first term of a sequence is 9. Each term after the first is 4 times the preceding term. If w represents the nth term of the sequence, which equation gives w in terms of n?
a. w=9(4ⁿ)
b. w=4(9ⁿ⁻¹)
c. w=9(4ⁿ⁻¹)
d. w=4(9ⁿ)