A monopolistically competitive industry that earns economic profits in the short run will . A. continue to earn economic profits in the long run B. experience the entry of new rival firms into the industry in the long run C. experience the exit of existing firms out of the industry in the long run

b or d if i'm correct boi.

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.