Daniel derives utility from only two goods, cake (Qc) and donuts (Qd). The marginal utility that Daniel receives from cake (MUc) and donuts (MUd) are given as follows:

MUc = Qd

MUd = Qc

Daniel has an income of $240 and the price of cake (Pc) and donuts (Pd) are both $3.

See Scenario 4.1. Holding Daniel's income and Pd constant at $240 and $3 respectively, what is Daniel's demand curve for cake?

a.

Qc = 240 - Pc

b.

Qc = 120/Pc

c.

None of these

d.

Qc = 240/(3 + Pc)

e.

Qc = 240/Pc