With respect to the major participants in the advertising and promotions process, which of the following participants include sales promotion agencies, digital/interactive agencies, and public relations firms?

Specialized marketing communications service agencies

Explanation:

Based on the information provided within the question it can be said that the major participant that includes these are Specialized marketing communications service agencies. These agencies provide specific marketing communications services to other organizations, and include sales promotion agencies, digital/interactive agencies, and even public relations firms to deal with all aspects of marketing.

c, theres a double tax on the business earnings

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.