How is an exponential growth function of the form ​f(x)=a(1+r)^x related to an exponential function of the form ​f(x)=a*b^x?

The value of a is the initial​ amount, and b is equal to the growth factor ​(1+​r).
B.
The value of a is the initial​ amount, and b is equal to the growth factor r.
C.
The value of a is the growth​ factor, and b is equal to the initial amount ​(1​+r).
D.
The value of a is the growth​ factor, and b is equal to the initial amount r.