Concerning the Inland Navigation Rules, what is true?

The correct choice emphasizes the requirement for vessels to comply with Vessel Traffic Service (VTS) regulations under the Inland Navigation Rules. VTS systems are designed to enhance the safety and efficiency of vessel traffic in busy or congested waters. They provide information to mariners about navigation conditions and traffic and help manage the movement of vessels.

Compliance with VTS regulations is crucial as these services assist in preventing collisions and facilitate the safe transit of vessels in areas where navigation may be more complex. While communication and traffic separation schemes are certainly important aspects of safe navigation, the distinct obligation to adhere to VTS regulations underlines the necessity for vessel operators to engage with and follow established practices in these monitored waters. This has a significant impact on maritime safety and efficiency.

The other options, while relevant to the broader context of navigation rules, do not encapsulate the specific compliance requirements set forth by the Inland Navigation Rules as comprehensively as option C does.