Which weather scenario may lead to severe in-flight icing?

Severe in-flight icing primarily occurs when supercooled water droplets are present, particularly when they can splash on impact with the aircraft’s surfaces. The correct scenario describes droplets that splash on impact at temperatures below 0 degrees Celsius. This situation is critical because even if the surrounding air temperature is below freezing, if the droplets remain in a liquid state due to being supercooled, they can freeze upon contact with the aircraft, creating ice accumulation.

Supercooled droplets are particularly dangerous, as they are often not visible to pilots and can lead to rapid icing conditions, which can affect the aircraft's performance and safety. The impact of these droplets freezes upon contact, leading to the formation of significant ice accumulation which can be detrimental during flight, especially if the build-up is on critical surfaces such as wings or tail sections.

Other scenarios can lead to icing, but they may not be as severe under the specific conditions described in option A. Therefore, understanding the encounter with supercooled droplets and their freezing characteristics is vital for recognizing and predicting severe icing conditions during flight.