Answer:
The given statement:
The base of an exponential function can only be a positive number is a TRUE statement.
Step-by-step explanation:
In mathematics, an exponential function is a function of the form

where b is a positive real number, and in which the argument x occurs as an exponent and a is a constant which can be both positive as well as negative.
The term 'b' is called base of the exponential function.
Hence, the base of an exponential function can only be a positive number.