A Perfectly-Competitive, Profit-Maximizing Firm's Total Cost Equation Is TC =

A perfectly-competitive, profit-maximizing firm's total cost equation is TC = 1,500 + 5Q + 0.0025Q². The market-clearing price is $25. The firm's profit-maximizing level of output is:

A) 500 units.
B) 633 units.
C) 1,500 units.
D) 3,500 units.
E) 4,000 units.