Final answer:
The firm fills its customer's orders from finished goods inventory using a Just in Time (JIT) inventory system.
Step-by-step explanation:
The correct answer is 1) Just in Time (JIT) inventory system.
In a Just in Time (JIT) inventory system, the firm fills its customer's orders from finished goods inventory. JIT is a system where inventory is kept minimal, and products are produced and delivered as needed. This helps reduce inventory holding costs and improves efficiency in the production process.
An example of a firm using JIT is a fast-food restaurant that prepares food as orders come in, rather than pre-cooking and holding the food in inventory.