The correct answer is B. 30% . Inventory holding cost is the annual cost of carrying inventory, usually expressed as a percentage of inventory value. It includes the cost of capital tied up in stock, storage space, handling, insurance, taxes, deterioration, obsolescence, shrinkage, administration, and inventory-control effort. In maintenance storerooms, this is a serious Work Execution Management issue because spares must be available to execute planned and corrective work, but excessive inventory wastes capital and hides poor materials-management discipline. A 20% assumption may be too low for many maintenance environments, especially where obsolete, slow-moving, or poorly controlled spares exist. A 40% assumption may occur in poor inventory systems but is high as a typical answer. The commonly used practical estimate is around 30% annually. For a $2 million inventory, that means the organization may be carrying approximately $600,000 per year in holding cost. CRL reliability leaders must therefore balance service level, criticality, stockout risk, and carrying cost instead of simply increasing or cutting inventory blindly.