Question: In the context of Overload Control, what happens when timer `TinTC` expires at the Core Network (CN) side during step-by-step reduction of traffic due to overload?
Option 1: The CN immediately stops all signalling traffic to alleviate the overload.
Option 2: The CN ignores the expiration and continues with the current traffic reduction level.
Option 3: The CN reduces the traffic by an additional step as a precautionary measure.
Option 4: The CN increases the traffic by one step and re-starts timer `TinTC`, unless already at zero reduction steps.
Explanation: When `TinTC` expires at the CN side, it triggers a scheduled increase in traffic as part of step-by-step adjustment. The CN increases traffic by one step and restarts `TinTC`, unless at zero reduction steps, to dynamically manage overload while minimizing service impact.