Which document must be actively maintained by a regulated seller regarding SLCP sales?

The correct choice for the document that must be actively maintained by a regulated seller concerning SLCP (Scheduled Listed Chemical Products) sales is the employee training records. This is vital because proper training ensures that employees understand regulations surrounding the sale of controlled substances, including SLCPs, and compliance with applicable laws.

Maintaining comprehensive training records helps demonstrate that the seller has adequately prepared their staff to handle these products responsibly, identify suspicious transactions, and adhere to legal requirements. Moreover, it is critical for audits and inspections by regulatory agencies, ensuring that the seller meets all regulatory compliance standards.

Other documents like marketing materials and sales data reports, while important for business operations, do not specifically address the training and compliance aspect regarding SLCPs. Customer purchase logs are also important, but they are more focused on transaction history rather than employee preparedness and compliance with legal obligations. Therefore, the active maintenance of employee training records is essential for ensuring safe and legal sales practices related to SLCPs.