What conditions are most likely to lead to the formation of hill fog?

Question

Question ATPL - Airline Transport Pilot license - Meteorology

QuizVDS · Accepted Answer

Humid stable air mass, wind blowing towards the hills.

QuizVDS · Answer

High relative humidity and an unstable air mass.

QuizVDS · Answer

Clear skies, calm or light winds, with relatively low humidity.

QuizVDS · Answer

Precipitation which is lifted by the action of moderate winds striking the range.

Id 407 - ATPL - What conditions are most likely to lead to the formation of hill fog?