Which of the following represents a “trace” level of icing?

The term "trace" level of icing refers to the smallest amount of ice accumulation that can be detected, which typically means that there is only a very thin layer of ice forming on the aircraft. This level of icing is often considered negligible and may not cause significant operational issues, although pilots should remain vigilant as conditions can change and lead to more severe icing.

In contrast, light, moderate, and severe icing levels indicate increasing amounts of ice accumulation, which can negatively impact aircraft performance, control, and safety. For example, light icing can begin to create some operational challenges, moderate icing can restrict aircraft performance significantly, and severe icing can lead to dangerous conditions. Thus, "minimal accumulation" accurately captures the essence of the trace icing level, signifying that the ice is present but not yet posing a threat to safe flight operations.