Assume the firm must pay each unit of labor a wage of $4 (w=4) and each unit of capital a rental rate of $1 (r=1). In the short-run, the firm's capital is fixed at 16 units (Kbar=16) and the firm is maximizing their profits by producing 8 units of output (q=8).

Which one of the statements below must be true:

a.) The cost of producing 8 units of output is the same in the long-run and the short-run.

b.) The cost of producing 8 units of output is lower in the long-run.

c.) The cost of producing 8 units of output is higher in the long-run.