What is a symbol?
a specific icon used to indicate a feature such as rocks
a specific icon used to indicate a feature such as letters
a table defining the colors, letters, and keys such as rocks
a table defining the colors, letters, and keys such as letters

The images show two different fronts.which fronts are shown? item a shows a cold front, and item b shows a warm front.item a shows an occluded front, and item b shows a cold front.item a shows a warm front, and item b shows a stationary front.item a shows a stationary front, and item b shows an occluded front.