Explain how current and oxygen content affect the biodiversity of streams and rivers

The oxygen content at the source of the streams or rivers is higher as compared to the mouth of the river. Consequently, the organisms which require more oxygen tend to find at the source of the rivers whereas the organisms which require less oxygen tend to find at the mouth of the river.

Explanation:

well for one plants are always the producer, so a is the answer. a wolf is more of the consumer(predator) and the deer is the prey so i know those two are out of the question. also mushrooms are fungi/fungus so a is the producer.