According to the NEC, which statement is true regarding receptacles?

The statement that receptacles must be listed and marked with the manufacturer's name is true according to the National Electrical Code (NEC). This requirement ensures safety and compliance with industry standards, as it verifies that the receptacles have been tested and meet specific performance criteria. The listing by a recognized testing laboratory indicates that the product has undergone rigorous assessment to ensure it is safe for use. Proper marking also facilitates accountability and traceability for consumers and electricians, allowing for easy identification if an issue arises regarding the product.

In contrast, the other options do not align with NEC requirements. For example, there is no NEC mandate for receptacles to be painted for identification, as this could introduce unnecessary variables and complexities. Similarly, receptacles are not restricted to being made only of plastic; they can be made from various materials that comply with safety standards. Lastly, stating that receptacles need no specific markings would contradict the NEC's emphasis on safety and proper identification, making the correct answer clear in this context.