32, 16, 8, 4, 2,

find the common ratio of the given sequence, and write an exponential function which represents the sequence.
a) 2; f(x) = 32(2)x-1
b)
1
2
; f(x) = 32x-1
c) 2; f(x) = 32(
1
2
)x-1
d)
1
2
; f(x) = 32(
1
2
)x-1