What is a metric for the cost dimension of a process?

The correct choice highlights a metric that directly measures a specific aspect of the cost dimension of a process. Labor cost per unit is a clear and quantitative measure that reflects the direct expenses associated with producing each unit of a product or service. This metric allows organizations to assess efficiency and profitability, as it provides insights into how much labor is being effectively utilized in the production process relative to the output.

Understanding labor costs is crucial for organizations focused on optimizing their financial performance. It enables better budgeting, cost control, and pricing strategies, thus allowing firms to identify areas where efficiencies can be improved and costs can be reduced. While the other options pertain to various operational aspects, they do not directly address the cost dimension in the same manner. For example, production cycle time and equipment downtime are metrics related to process efficiency, and inventory supply days relates more to inventory management than to direct cost assessment.