Which scenario represents appropriate disposal of old client records by a behavior analyst?

The appropriate disposal of old client records by a behavior analyst is best represented by the action of shredding the records while using codes to track them. This approach adheres to ethical and professional standards concerning confidentiality and privacy. Shredding ensures that sensitive client information is destroyed in a way that prevents unauthorized access or retrieval, which is crucial in maintaining client confidentiality.

By using codes for tracking, Mark still maintains some level of organization and accountability regarding the records disposed of, while ensuring that no personally identifiable information is exposed. This method reflects a commitment to ethical responsibilities and is in line with best practices for handling confidential client information.

In contrast, the other scenarios do not sufficiently protect client information. Disposing of records in the garbage or at a dumpster could easily lead to exposure of private information, which violates confidentiality ethics. Keeping records locked without shredding them doesn't resolve the risk of past clients’ information being compromised if the locked records are breached or accessed without authorization. Therefore, the action of shredding while using codes strikes the right balance between thoroughness in disposal and maintaining a professional standard.