The correct answer is A. If the marginal cost of the labor curve lies above the labor supply curve, the firm is likely a monopsony.

A monopsony is a market structure in which firms are authorized to employ the labor factor of production. In the monopsony structure, the workers are paid similar wages hence causing a change in the overall cost required to hire one more worker. This increases the labor's marginal factor cost, causing it to be above the labor supply curve.