What purpose does a key have on a map a to show direction

b to explain symbols, colors, and lines

c to reveal what area the map will cover

d to tell how a measured space corresponds to actual distance
pls hurry

B - To explain symbols, colors, and lines.

the first settlements began along the huang river because of the importance of the huang river in the beginning of china. it goes back to the story, “the tale of emperor yu”, which references the tale of the great flood, which was caused by the huang river and was believed to create and influence china’s making.

if you are on the computer you can not take a picture but you can upload one but i am not sure about phones but i'm pretty sure it's the but to upload one just click the paper clip looking thing/ link thingy thing and upload a pic