A profit-maximising firm hires workers in a perfectly competitive labour market but has monopoly power in its product market. The firm's short-run demand curve for labour is derived from its:
marginal physical product of labour multiplied by the price of the output (MPPL×PMPP_L \times PMPPL×P)
average physical product of labour multiplied by the marginal revenue of the output (APPL×MRAPP_L \times MRAPPL×MR)
marginal physical product of labour multiplied by the marginal revenue of the output (MPPL×MRMPP_L \times MRMPPL×MR)
marginal cost of labour multiplied by the price of the output (MCL×PMCL \times PMCL×P)