Identify the NEMA standard symbol for an SPST NC, single-break switch.

The NEMA standard symbol for an SPST NC (Single Pole Single Throw Normally Closed) switch is indeed represented by the symbol II. This designation is specifically used to indicate that the switch will allow current to flow when it is in its resting state (normally closed) and will break the circuit when actuated (opened). This is crucial in many applications where the normal state requires the circuit to be on, and operation of the switch is necessary to turn it off.

In practical terms, understanding this symbol helps electrical professionals quickly identify the functionality of various switches in their systems, ensuring they can efficiently design and troubleshoot circuits.

The options related to other symbols correspond to different types of switches or control devices, which do not reflect the characteristics of a single-pole, single-throw, normally closed switch. Knowing the specific NEMA symbols aids in error prevention and ensures that components are correctly utilized in electrical installations.