Monetary costs and opportunity costs are always identical

A consumer has $100 to be spent on tables and chairs. If his income increases to $200, the prices of the goods remaining unchanged, his budget constraint:

A) pivots to the left along the vertical axis. B) pivots to the right along the horizontal axis. C) shifts to the left. D) shifts to the right.

There are only two firms in an industry with demand curves q1 = 30 - P and q2 = 30 - P. Both have no fixed costs and each has a marginal cost of 10 per unit produced. If they behave as profit-maximizing price takers, each produces 20 units and sells them at a price of 10 so that each firm makes zero economic profits. If they formed a cartel, the profit-maximizing price is

A) 10. B) 15. C) 20. D) 25.