Which of the following describes exponential decay?
A.) The amount at a given time can be calculated by subtracting an amount from the previous amount.
B.) The amount at a given time can be calculated by adding an amount to the previous amount.
C.) The amount at a given time can be calculated by multiplying the previous amount by a value less than 1.
D.) The amount at a given time can be calculated by multiplying the previous amount by a value greater than 1.