Question: In a PSS (Packet-switched Streaming Service) interaction, if a client includes a "Supported" SP header field in a request but the server's response does not contain this header field, what should the client assume about the server's support for the indicated features?
Option 1: The server supports all the listed features by default.
Option 2: The server supports none of the indicated features.
Option 3: The server's support for the features is unknown and requires further inquiry.
Option 4: The client should retry the request without the "Supported" header to confirm support.
Explanation: According to the protocol, if an SP request includes a "Supported" header but the corresponding response does not include this header field, the PSS client shall assume that the PSS server does not support any of the indicated features. This ensures clarity in capability negotiation between the client and server, avoiding potential misunderstandings about supported extensions.