Answer:

Step-by-step explanation:
<u>Exponential Growth Function
</u>
The exponential function is often used to model natural growing or decaying processes, where the change is proportional to the actual quantity.
An exponential growth function is expressed as:

Where:
C(t) is the actual value of the function at time t
Co is the initial value of C at t=0
r is the (positive) growth rate, expressed in decimal
Since r is positive, 1+r is greater than 1.
From the available options, only the last two of them correspond to exponential functions according to the definition above.
Note the third option has a base of 1/3 which is not greater than 1. In fact, it corresponds to an exponential decay function.
The last option has a base 3 and corresponds to a value of r=2 which correctly fits with the definition presented above, thus the correct choice is
