Which of the following codes are used for non-ambulatory services?

The correct choice for non-ambulatory services is represented by G codes. G codes are specifically used for reporting non-ambulatory and other unique services or procedures that are not accounted for under other coding systems. They play a crucial role in documenting certain services, integrated therapies, and therapies that might not have specific codes otherwise.

K codes, on the other hand, are typically used for durable medical equipment (DME) for beneficiaries under Medicare and are not specifically focused on non-ambulatory services. C codes relate to hospital outpatient services, primarily for hospitals to report their cost and service efficiency. M codes are used for certain medical services and procedures but are not designed specifically for non-ambulatory service needs. Therefore, G codes are the most appropriate and relevant choice in this context.