What is the characteristic of an exponential function? (Please explain why) A. As the x-value increases, an exponential function increases or decreases very slowly.
B. As the x-value increases, an exponential function increases or decreases at a constant rate.
C. As the x-value increases, an exponential function is always represented by a straight line.
D. As the x-value increases, an exponential function increases or decreases very quickly.