Any portion of a refrigerant system that is subject to physical damage must be _____ in an approved manner.

In this context, the term "protected" refers to the need for refrigerant system components that are vulnerable to physical damage to be safeguarded in a way that prevents harm or deterioration. The North Carolina Mechanical Code emphasizes the importance of ensuring the integrity and safe operation of mechanical systems, including refrigerant systems.

When a portion of a refrigerant system is at risk of physical damage, it is essential to implement protection measures that may include barriers, guards, or secure installation methods. This could involve using protective enclosures or supports that can withstand potential impacts or environmental factors, thus maintaining the system's functionality and safety.

Other choices, such as "insulated," "shielded," and "contained," imply different concepts. Insulation primarily addresses temperature regulation and energy efficiency, while shielding could suggest a specific type of physical barrier that does not necessarily cover all aspects of protection. Containment often refers to keeping fluids or materials within a designated area but does not encompass the broader concept of protecting against physical damage. Hence, "protected" is the most comprehensive and accurate term for this situation.