Which form of business organization is the least common in the United States?

Refer to the scenario above. What is Sarah's opportunity cost of producing one greeting card?

A) 0.33 earrings B) 0.5 earrings C) 1 earring D) 3 earrings

In the above figure, if the firm is in monopolistic competition, its price will be

A) $1. B) $2. C) $3. D) $4.