Question: In a PSS (Packet-switched Streaming Service) client, what is the primary purpose of the `MaxPolyphony` attribute in the `PssCommon` component?
Option 1: To indicate the device's support for stereo audio playback.
Option 2: To signal the maximum number of simultaneous GM1 voices supported by the synthetic audio engine.
Option 3: To define the rendering screen size of the device in pixels for PSS media presentation.
Option 4: To specify the maximal polyphony capabilities supported by the PSS client, particularly for Scalable Polyphony MIDI content.
Explanation: The `MaxPolyphony` attribute is crucial for signaling the maximum polyphony capabilities of a PSS client, which directly impacts its ability to handle complex MIDI content, such as Scalable Polyphony MIDI (SP-MIDI) with Channel Masking. This attribute ensures compatibility between the client's capabilities and the delivered content.