Which of the Following Is a Common Mistake Managers Make

Which of the following is a common mistake managers make?

A) Using marginal analysis to make output decisions.
B) Maximizing the value of the firm instead of maximizing the firm's profits.
C) Treating implicit opportunity costs as part of the total costs of using resources.
D) Increasing the rate of production in order to reduce unit costs of production.
E) all of the above.