If the market for a product is broadly defined, then A. the expenditure on the good is likely to make up a large share of one's budget. B. there are many substitutes for the product and the demand for the product is relatively elastic. C. the good has many complements. D. there are few substitutes for the product and the demand for the product is relatively inelastic.

The correct answer is letter "D": there are few substitutes for the product and the demand for the product is relatively inelastic.

Explanation:

Broad markets are those offering products that are not easy to substitute. Electricity is an example of a service that is not easy to substitute. Most narrow markets are monopolies, thus, they are characterized by having an inelastic demand meaning their quantity demanded does not change in front of changes in prices.

answer: marginal utility of the fourth brownie is 0.

explanation: marginal utility is the addtional utility gained from the consumption of one more unit of a good. it is given by,

so, marginal utility at the 4th unit will be given by

since, the values are not given here, you can simply find marginal utility at fourth unit by subtracting total utility at 3rd unit from total utility at 4th unit.