Assume a perfectly competitive firm is producing 300 units of output, P = $10, ATC of the 300th unit is $8, marginal cost of the 300th unit = $10, and AVC of the 300th unit = $6. Based on this information, the firm is
a. earning an economic profit of $600.
b. earning an economic profit of $1,200.
c. incurring a loss of $600.
d. incurring a loss of $1,200.