Assume a perfectly competitive firm is producing 500 units of output, P = $7, ATC of the 500th unit is $6, marginal cost of the 500th unit = $7, and AVC of the 500th unit = $5. Based on this information, the firm is:
A) earning an economic profit of $500.
B) incurring a loss of $1,000.
C) incurring a loss of $500.
D) earning an economic profit of $1,000.
Show how you arrived at your choice.