Answer: The correct answer is 1%: exponential decay.
Explanation: We are given a function:
...(1)
To determine the percentage rate of change in function, we compare the given function with the general form of exponent function, which is:
...(2)
Comparing both the equations, we get:


We take 'r' in percentage, so converting this above value in percentage, we get:

As the value of 'r' is negative, it means that the exponent is decaying, so the percentage rate of change in function will be 1% and it will be exponential decay.