Choose the most appropriate adjective.
During the winters, the valleys tend to be ___________ than the hilltops

foggier

The correct adjective to use in the blank is foggier. (OPTION 1)

The word foggier is the comparative form of the adjective foggy, which means that it indicates a higher degree of fogginess than foggy. In this case, during the winters, the valleys tend to be foggier than the hilltops, which means that there is more fog in the valleys than in the hilltops.