What might cause the MASTER WARN lights to activate?

The activation of the MASTER WARN lights can be attributed to various critical conditions within an aircraft, indicating situations that require immediate attention from the flight crew. In this case, all of the listed scenarios contribute to the activation of these warning lights.

An uncommanded feather refers to a condition where a propeller unexpectedly changes its blade angle to a low pitch without any command input from the pilot. This can lead to significant changes in thrust and may necessitate immediate corrective actions to maintain control of the aircraft.

A power step change relates to significant or rapid alterations in engine power output, which could also affect the performance and control of the aircraft. Such abrupt changes can be indicative of mechanical issues, representing a potential failure scenario that warrants immediate awareness and response from the crew.

Engine failure is perhaps the most critical event that can cause the MASTER WARN lights to illuminate. The loss of engine power can drastically affect the aircraft's ability to climb and maintain stable flight, necessitating immediate corrective actions and emergency procedures.

Since each of these situations poses a serious risk to flight safety and requires prompt crew intervention, it is accurate to conclude that all of them can lead to the activation of the MASTER WARN lights.