What is a solvent? O a relative quantity of molecules in a given space
O a different concentration of solute in a solution
O a substance that is dissolved in a solution
O a substance that dissolves a solute

The last one

Explanation:

A solvent is a substance that dissolves a solute

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.