Which of the following is NOT a required controlled substance record that must be maintained by the pharmacy?

The correct response identifies that reports of customer complaints are not a required controlled substance record that must be maintained by the pharmacy. In the context of controlled substances, the DEA mandates certain records to ensure compliance with the regulations governing the handling of such medications.

Executed order forms, records of dispensed medications, and the DEA registration certificate are all critical documents that pharmacies are required to maintain. Executed order forms are necessary for tracking the purchase and transfer of controlled substances, while records of dispensed medications keep a detailed account of how controlled substances are provided to patients, ensuring accountability and adherence to legal requirements. The DEA registration certificate is essential as it verifies that a pharmacy is authorized to handle controlled substances.

While customer complaint reports may be important for overall pharmacy operations and quality assurance, they do not fall under the category of mandatory records related to controlled substances as stipulated by DEA regulations. Therefore, option C is the correct answer, as it indicates a document that is not legally required to be maintained in relation to controlled substances.