The two models that are commonly used to explain the relationship between advertising and sales are the:
A. concave-downward function and the S-shaped response function.
B. S-shaped response function and the concave-upward function.
C. marginal utility function and the S-shaped demand function.
D. S-shaped demand function and the convex-downward function.
E. concave-upward function and the S-shaped demand function.
Answer: A