Why Does a Monopsony's Marginal Cost of Labor (MCL)curve Lie

Why does a monopsony's marginal cost of labor (MCL) curve lie above the market supply of labor curve? Because the monopsony

A) Must raise the wage it pays all employees in order to attract and hire additional workers
B) Must pay higher wages to only the last workers hired in order to attract and hire additional workers
C) Faces the market demand and marginal revenue curves
D) Must lower the wage it pays all employees in order to maintain profitability
E) Has such high labor costs relative to the supply of labor