Which of the following is categorized as an external failure cost?

External failure costs refer to the expenses incurred when a product or service fails to perform as intended after it has been delivered to the customer. These costs arise when customers have to deal with issues that are a direct result of the organization's failure to meet quality standards.

The correct choice involves costs related to returns and repairs, which are directly tied to issues that customers experience with products or services. When a customer receives a defective product, the organization must incur costs to facilitate the return process, repair the product, or possibly replace it. This can lead to customer dissatisfaction and damage to the brand's reputation, further emphasizing why these costs are categorized as external failures.

In contrast, the other options represent costs that are more related to processes within the organization or preventative measures. Costs associated with testing and inspection are internal to the production process and aim to catch defects before products reach the customer. Similarly, costs from a lack of training and costs for maintaining quality standards are preventative and internal costs not categorized as external failures, as they do not arise from issues that affect the customer directly post-delivery.