There are times when a situation becomes critical, time is running out, you have lost contact with someone whose guidance is critical in an expedition or a plane crash but you have to act fast to save your own life and, maybe, the lives of many others.
A situation can also occur which becomes a turning point in your life. This is not at all serious. You are offered an important job for which you have no previous experience or training but you have to take a decision immediately based on your own gut feeling. Professional consultants often face such situations by risking their reputation if they fail in the assignment.
Sometimes a dangerous situation can arise when someone starts shooting at random and nobody knows how to deal with a mass murderer. Somebody in the crowd takes a “mad’ decision to attack the murderer by risking his own life to save others before the police arrives.
You can answer based on your own experience or a published news story.