Agood is nonrivalrous in consumption ifa. its consumption by one person does not reduce its consumption by othersb. its consumption by one person reduces its consumption by othersc. it is possible, or not prohibitively costly, to exclude someone from receiving the benefits of the good once it has been producedd. it is impossible, or prohibitively costly, to exclude someone from receiving the benefits of the good once it has been producede. a and d

Option(a) is correct.

Explanation:

The goods are non rivalrous in nature if its consumption by one person doesn't reduce the supply of that for the other person or we can say that the utility derived from that good after the consumption by one person remains the same.

These are the public goods in which we cannot exclude someone from consuming it.

There are certain examples of public goods such as street lights, beaches, public parks,etc.

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.