Which water sources contribute to a river system? Select three options.
1. groundwater
2. lakes
3. rivers
4. streams
5. watersheds

Groundwater, streams and lakes

2. Lakes

3. Rivers

4. Watersheds

Explanation:

A river system is a system that consist of a bunch of different rivers that drain into a bigger body of water for example a lake or a ocean. "Rivers" would be one of the answers because its a RIVER system so obviously rivers are going to be involved. "Lakes" is going to be the second answer because a river system drains into a lake or ocean. Then the last answer will be "watersheds" because watersheds are ridges that help separate waters that are flowing into different rivers or lakes or oceans.

Hope this helps.