The amount of radioactive uranium changes with time. the table below shows the amount of radioactive uranium f(t) left after time t:

t(hours) 0 0.5 1
f(t) 100 50 25

which exponential function best represents the relationship between f(t) and t?

a).f(t) = 100(0.25)t

b).f(t) = 0.25(100)t

c).f(t) = 100 (0.5)t

d).f(t) = 0.25(50)t