Question: In a Transparent end-to-end Packet-switched Streaming Service (PSS), what does the presence of the '3GPP-Adaptation-Support' attribute in an SDP signal to a client, and what action is the client expected to take if it supports bit-rate adaptation?
Option 1: The server's capability for encryption; the client should then prioritize secure streaming protocols.
Option 2: The server's support for multiple streaming formats; the client should respond with its preferred format.
Option 3: The server's provision of rate adaptation; the client shall use the '3GPP-Adaptation' header and include a CP Next Application Data Unit (NADU) APP packet for reporting at the specified report frequency.
Option 4: The server's requirement for Quality of Service (QoS) feedback; the client should periodically send QoS reports.
Explanation: The '3GPP-Adaptation-Support' attribute signals to the client that the server can adapt the bit-rate of the streaming service. If the client also supports this feature, it is expected to utilize the '3GPP-Adaptation' header in subsequent signaling and include NADU APP packets at the interval specified by the report-frequency value, facilitating efficient rate adaptation.