Which type of connector is typically used with flexible conduit systems?

Flexible Metal Conduit (FMC) connectors are specifically designed to work with flexible conduit systems, making them the most appropriate choice among the options provided. FMC connectors provide a secure and reliable method of connecting flexible metal conduit to various types of enclosures or junction boxes. This type of connector is constructed to accommodate the movement and flexibility inherent in FMC, while also maintaining proper grounding and protection.

Duplex connectors are generally used in applications involving duplex outlets, and are not specialized for conduit systems. AC/MC connectors refer to connectors for armored cable and metal-clad cable, which do not function the same way as FMC connectors. Adapter connectors might be used to convert between different types of fittings, but they lack the specific design characteristics needed for secure connections with flexible conduits.