Question: What should a receiving GTP-C entity do when it receives an incoming Initial message without a message priority in the GTP-C header?
Option 1: Ignore the message and wait for a retransmission.
Option 2: Apply a default priority to the message.
Option 3: Use the message priority from the last received message.
Option 4: Drop the message to prevent overload.
Explanation: According to the text, when messages do not have a message priority in the GTP-C header, the receiving GTP-C entity shall apply a default priority if the incoming message is an Initial message. This ensures that the message is processed with a minimum level of priority even if no explicit priority was signalled.