Without sunlight plants can undergo photsynthesis and cannot produce oxygen for humans to breathe and would cause the humankind to go extinct.
Here are the answers.
1. Runoff from the land in a <em>stream’s watershed</em>……….
2. And water from its <em>tributaries</em>.
3. At the stream’s headwaters, the <em>gradient</em>………..
4. The greater the water speed, the larger the <em>stream load</em>………..
5. Which is made up of: a) <em>suspended load</em>, b) <em>dissolved load</em>, c) <em>bed load</em>
6. Under these conditions a <em>braided stream</em> may form
7. Where gradient flattens, a <em>meander</em> may form
I honestly think that a or d would be the best options. I would start with D and if that doesn't work try a.