Final answer:
External failure costs are likely to be the most expensive cost of quality.
Step-by-step explanation:
The most expensive cost of quality among the options listed is External failure costs.
External failure costs refer to the costs incurred when a defective product reaches the customer and causes harm or dissatisfaction. Examples of external failure costs include product recalls, warranty claims, and customer returns. These costs can be significant as they not only involve financial expenses but also damage to the company's reputation.
On the other hand, Appraisal costs are associated with the evaluation of products or services to ensure they meet quality standards. These costs include inspection, testing, and auditing. Internal failure costs are incurred when defects are identified before the product reaches the customer. These costs include rework, machine repairs, and scrap. Lastly, Prevention costs are related to activities aimed at preventing defects from occurring in the first place, such as employee training, process improvement, and quality planning.