Midge added some chlorine to the water in a pool. the chlorine evaporated at a fixed rate every week. the table below shows the amount of chlorine f(n), in ounces, that was left in the pool after n weeks:

n f(n)
1 16
2 8
3 4
4 2

which function best shows the relationship between n and f(n)?
f(n) = 16(0.5)n − 1
f(n) = 32(0.5)n − 1
f(n) = 16(0.5)n
f(n) = 32(0.5)n + 1