A positive economic profit signals that the investors of a firm should divert their funds to alternative ventures

Why is it that the consumer can maximize total net utility only if the purchase quantity brings marginal utility as close as possible to equality with price?

For a monopsonist the marginal cost of increasing its workforce will always be greater than the wage rate because

A) there is not good factor substitution in a monopsony. B) the wage rate offered the newest employee must be paid to all workers. C) the industry will be a closed shop. D) a normal rate of return must be paid to the owner.