Which of the following is not a reason why some workers are paid above the equilibrium wage? a. Labor unions b. Minimum-wage laws c. Monopsony power of large firms d. Efficiency wages

**Step 1: Understand the Question** We are asked to identify which option is not a reason for some workers being paid above the equilibrium wage. **Step 2: Analyze Each Option** - **Option (a) Labor unions:** Labor unions often negotiate for wages above the competitive equilibrium to secure better wages for their members. - **Option (b) Minimum-wage laws:** Minimum-wage laws set a floor on wages. This legal minimum is typically above the equilibrium wage in a competitive market. - **Option (c) Monopsony power of large firms:** In a monopsony, a single or few employers have significant market power. This allows these employers to pay wages below the competitive equilibrium, not above it. - **Option (d) Efficiency wages:** Efficiency wage theory suggests that paying workers above the equilibrium wage can increase productivity, reduce turnover, and attract higher quality applicants. **Step 3: Conclusion** Since options (a), (b), and (d) are all reasons why workers might be paid above the equilibrium wage, the incorrect reason is: \[ \textbf{(c) Monopsony power of large firms} \] **Final Answer: (c) Monopsony power of large firms**