Answer:
Exponential Decay
Explanation:
Here, The given function is,

Where, x is written as exponent of 1/3.
Since, If x ( input value of a function ) as exponent of any number then it would be exponent function.
⇒ f(x) is an exponential function,
Now, if an exponential function is,

Then, for the value 0<b<1, the function is decay.
While, for, the value of b>1, the function is growth.
Here, b = 1/3 and 0 < 1/3 < 1,
Thus, the given function is Exponential Decay