Question: In an MBMS download session using FLUTE, which reception approach requires prior knowledge of file identifiers (fileURIs) and ensures an upper bound to the quantity of files downloaded, while also accommodating updates to those files?
Option 1: Promiscuous Reception
Option 2: One-copy Reception with Optional Updates
Option 3: Keep-updated Reception without Prior Knowledge
Option 4: Keep-updated Reception with Prior Knowledge of File Identifiers
Explanation: The correct answer is "Keep-updated Reception with Prior Knowledge of File Identifiers" because this approach, as described in the context of MBMS download using FLUTE, specifically requires prior knowledge of file identifiers (fileURIs) to receive one or more specific files and continue to receive any updates to those files. This ensures an upper bound to the quantity of files downloaded, making it efficient for managing predictable and unpredictable file updates over time.