Question

what does the nec article 200 contain information on?
identification of grounded conductors
rigid conduit wiring methods
low voltage communication systems
ceiling power distribution systems

Explanation:

NEC (National Electrical Code) Article 200 specifically deals with the identification of grounded conductors. Rigid conduit wiring methods are covered in other articles related to wiring methods. Low - voltage communication systems have their own set of articles (like Article 800 etc.). Ceiling power distribution systems are not the focus of Article 200.

Answer:

identification of grounded conductors