The demand equation for a monopolist's product is p = 500/√q, where p is the price per unit (in dollars) for q units. If the total cost c (in dollars) of producing q units is given by c = 5q + 2000, then the level of production at which profit is maximized is:
a) 1235 units
b) 100 units
c) 50 units
d) 2500 units
e) 750 units