Under COLREGs Rule 17 (Action by Stand-on Vessel), when is the stand-on vessel permitted or required to take action to avoid a collision?

1. She may take action as soon as it becomes apparent that the give-way vessel is not taking appropriate action, and MUST take action when collision cannot be avoided by the give-way vessel alone
2. She is forbidden from ever altering course or speed under any circumstances
3. She must immediately alter course to port as soon as the give-way vessel is sighted
4. She must stop her engine as soon as the give-way vessel reaches 5 nautical miles range