Answer the following question given this paragraph: 

Streams often start in mountains, where the land is very steep. You can see an example in Figure below . A mountain stream flows very quickly because of the steep slope. This causes a lot of erosion and very little deposition. The rapidly falling water digs down into the stream bed and makes it deeper. It carves a narrow, V-shaped channel.


Q: Where do streams often start?


A:
mountains