Which statement is correct regarding JSON?

The statement that Cisco has been adding JSON support on various device platforms is correct because JSON (JavaScript Object Notation) has become a universal data interchange format widely adopted in network devices and APIs for its simplicity and ease of use. Cisco, like many other technology companies, has recognized the importance of JSON for configuration, management, and monitoring tasks across its network devices. By integrating JSON support into their platforms, Cisco allows developers and network administrators to more easily utilize data formats that are common in modern web applications, thus improving interoperability and automation capabilities.

The other statements do not hold true. JSON is indeed suitable for validation when used in conjunction with schemas such as JSON Schema. It is not a markup language; rather, it is a lightweight data format derived from JavaScript. Additionally, JSON is frequently used in REST APIs, making it an integral part of modern web service architecture.