Marine debris is best described as being composed of
a. solid garbage
b. untreated sewage
c. toxic chemicals
d. things discarded by humans

Solid garbage

Explanation:

Marine debris are artificial objects that are lost or thrown into the marine environment. Majority of these debris include plastic, glass, metal, fishing hook etc.

All these examples mentioned above can be classified as solid garbage.

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.