What term describes the collection of all hardware, software, and firmware responsible for system security?

The term that describes the collection of all hardware, software, and firmware responsible for system security is the Trusted Computing Base (TCB). The TCB encompasses all the components critical to a system's security; it is what ensures that the system behaves in a secure manner and performs its security functions correctly.

The TCB includes the operating system, firmware, and hardware mechanisms that provide security controls, such as access policies, privilege management, and authentication measures. These components must work together effectively to provide a strong security foundation for the system.

In contrast, security architecture refers to the overarching design and structure that guides the implementation of security measures within a system, but it does not specifically refer to the individual components that make up the security foundation. The access control layer is a specific element that deals with how rights and permissions are managed but is not a comprehensive term for all components involved in system security. The system security kernel, while integral in managing access and providing a secure operating environment, only represents a subset of the TCB.

Thus, the Trusted Computing Base is the correct answer as it encapsulates the entire collection of the essential security components that collectively maintain system security.