_____ connectors shall not be concealed when used in installations of LFMC.
d) All of the above
See answer and applicable Code reference
The correct answer is: b) Angle
Article 350 of the NEC covers the use, installation and constructions specifications for liquidtight flexible metal conduit (LFMC) and associated fittings. As noted in 350.42, "angle connectors shall not be concealed."