Which of the Following Statements Is True

Multiple Choice

Which of the following statements is true?

A) The short run is always somewhere between six and twelve months.
B) In the short run, changes in output can only be brought about by a change in the quantity of variable inputs.
C) The long run is any period of time over one year.
D) In the short run, there are variable costs but no fixed costs.
E) b and d