Answer:
C. The amount at a given time can be calculated by multiplying the previous amount by a value less than 1.
Step-by-step explanation:
Exponential decay is when an exponential function decreases per x-value. These functions go by a multiplier and are therefore, not linear, so you cannot add or subtract. Because the function is decaying, it is multiplying by an amount less than 1, since the multiplier is 1 - r, where r is the percent.