Can you posted picture of question

The graph is showing and exponential function that is a decay function.  You can recognize this by examining the base of the exponential term:

In general exponential functions can be expressed using:
y = ab^(x-h) + k  If the value of 'b' > 1 then you will have a function that rises from left to right, or an exponential growth.  If the value of 'b' is between 0 and 1 then you will have an exponential decay function which falls from left to right.

Looks like the only answer choice with a value of 'b' between 0 and 1 is choice A