What are the three choices that profit-maximizing firms have to make?
a. how much to demand, how to generate goods, and what to price outputted goods
b. how much to supply, how to produce output, and how much of each input to demand
c. how much to demand, how to produce input, and how much of each output to demand
d. how much to supply, how to market supplied goods, and how to advertise supplied goods

Four key marketing decision variables are price (p), advertising (a), transportation (t), and product quality (q). consumer demand (d) is influenced by these variables. the simplest model for describing demand in terms of these variables is: d = k – pp + aa + tt + qq where k, p, a, t, and q are constants. discuss the assumptions of this model. specifically, how does each variable affect demand? how do the variables influence each other? what limitations might this model have? how can it be improved?