Answer: OPTION C.
Step-by-step explanation:
The formula of Exponential Growth has the following form:

Where "C" is the initial value, "r" is the growth rate and "t" is the time in years.
In this case we have the following expression:

We can identify that:

Therefore, the meaning of the expression is: The initial number of trees planted by the agency is 1,500, and the growth rate is 2% per year.