The cost of statistical quality control in a product quality cost system is categorized as a(n):

A. Internal failure cost.
B. Training cost.
C. External failure cost.

D. Appraisal cost.

Explanation:
The following are the four categories of quality costs: prevention, appraisal, internal failure, and external failure (lost opportunity). Appraisal costs include quality control programs, inspection, and testing. However, some authorities regard statistical quality and process control as preventive activities because they not only detect faulty work but also allow for adjustment of processes to avoid future defects.