If a Consumer Must Spend Her Entire Income on Some

Multiple Choice

If a consumer must spend her entire income on some combination of two commodities and chooses to spend it all on just one of the commodities then:

A) the other commodity is an economic bad.
B) the other commodity must have zero marginal utility.
C) the other commodity generates less utility per dollar spent on the good.
D) the two commodities must be perfect substitutes.