Answer:
A. Time
Explanation:
The general formula for an exponential function is shown below:
where,
Ao = Initial amount
b = growth factor i.e come (1 + r)
r = growth rate
k = Constant
T = Time
Therefore the T describes the time
Hence, the first option is correct
To determine any of the above variable we simply used the above formula so the chances of thh correct answer could be high