Fact 1: Lakes are formed by precipitation and runoff.

Fact 2: The Caspian Sea is, strictly speaking, not really a sea but instead the world's largest lake.

Given the two facts above, answer the question "What was formed by precipitation and runoff?" with the following options: 
- a hydraulic system
 - streams.
 - The Caspian Sea
 - kalenchoes
 - near the shoreline
 - swamp vegetation
 - Calcium carbonate
 - patch reefs


 

   The Caspian Sea      