Find the exponential function that satisfies the given conditions: initial value = 70, decreasing at a rate of 0.43% per week

Answer choices:
A) f(t) = 70 x 0.9957^t
B) f(t) = 70 x 1.43^t
C) f(t) = 0.43 x 0.3^t
D) f(t) = 70 x 1.0043^t