What is the purpose of the key or legend on a map? a. it shows the meaning of the symbols used on the map. b. it provides definitions on unknown words and phrases. c. it makes the map more visually appealing to the reader. d. it explains the steps required to reach a certain point.

The correct option is A.
A map legend refers to the table or chart of visual explanation of the symbols that are used on a particular map. It serves as the key to understanding and reading the map correctly. Different colors are usually used to represent different features in order to show distinction among them. A map legend usually show symbols and the meaning of the of those symbols.