Which statement confirms the operability of RSVP in IntServ?

The statement that RSVP transmits QoS requirements effectively is correct because RSVP (Resource Reservation Protocol) is designed specifically to facilitate the reservation of resources across a network, enabling applications to communicate their Quality of Service (QoS) needs explicitly. It achieves this by allowing endpoints to send messages that specify the type and level of service they require. This functionality ensures that sufficient bandwidth and other necessary resources are reserved along the data path to meet the QoS demands of the applications, thus confirming its operability in the Integrated Services (IntServ) model, which relies heavily on such resource reservation capabilities.

The other statements don't accurately reflect RSVP's role in IntServ. For instance, while RSVP can be utilized by many applications, it is particularly tailored for applications that need a guaranteed level of service, making the first option broader than what RSVP is specifically designed for. The third statement that RSVP operates without maintaining flow status contradicts how RSVP functions; it actually requires maintenance of flow state information to effectively manage the reservations. Lastly, the idea that RSVP is a backup service for QoS misrepresents its purpose, as RSVP is not intended as a secondary or alternative method but rather as a primary mechanism for establishing QoS in the IntServ architecture.