A preliminary hearing officer may not order the production of which type of matters?

A preliminary hearing officer cannot order the production of privileged matters because these types of information are protected by legal rights or confidential relationships. Privileged matters typically include communication between an attorney and client, or other relationships that are considered confidential, such as doctor-patient communication. The protection of these matters exists to ensure that individuals can freely communicate within these relationships without fear of their statements being disclosed or used against them.

In contrast, non-privileged matters, general orders, and testimonial evidence do not have the same level of protection and can generally be ordered for production, making privileged matters the correct answer in this context.