Which of the following is classified as an internal failure cost?

The classification of internal failure costs encompasses costs that arise when a product or service fails to meet quality standards before it is delivered to the customer. This includes expenses associated with defects that are identified during the production process. Scrap and rework fall directly into this category, as they involve the costs incurred when products need to be discarded (scrap) or corrected (rework) to bring them up to quality standards before they can be sold.

This indicates that the correct answer highlights the essence of internal failure costs, which are primarily focused on rectifying issues that arise before the product reaches the market, thereby impacting production efficiency. In contrast, customer complaint visits and warranty costs are associated with failures that occur after the product has been delivered to the customer, placing them into external failure costs. While training of repair staff may be related to internal processes, it does not fall under internal failure costs because it does not represent a direct cost associated with a defective product.