Final answer:
If a device failure is frequently occurring due to end user misuse, the labeling is typically revised to provide clearer usage instructions. Option a.
Step-by-step explanation:
If a device failure is occurring with greater than expected frequency and an investigation of the problem implicates improper use by the end user, the labeling is revised option a. This is typically done to provide clearer instructions or warnings so that the end user can use the product correctly, reducing the chance of future failures due to improper use. This approach is usually less drastic than a recall or a total redesign of the product, and it can be an effective way to address issues that arise from misunderstandings of the proper use of a product. Issuing a "Dear Doctor" letter is more common in pharmaceutics, where it's used to inform healthcare professionals of important information about drugs, such as new side effects or instructions for use, not typically for device failure due to user error.