1. **State the problem:** 8 employees complete the inventory in 6 days. We want to find how long it takes if 4 more employees join, making 12 employees. 2. **Formula used:** Work done is constant. Work = Number of employees $ \times $ Time. 3. **Calculate total work:** $$\text{Work} = 8 \times 6 = 48 \text{ employee-days}$$ 4. **Find new time with 12 employees:** $$\text{Time} = \frac{\text{Work}}{\text{Number of employees}} = \frac{48}{12}$$ 5. **Simplify:** $$\frac{48}{\cancel{12}} = 4$$ 6. **Answer:** It will take 4 days for 12 employees to complete the inventory. This matches the option **4 days**.