If organisms like dolphins are found in a river region, why will river conservation be necessary?

Correct answer: Water quality and flow are linked with their life

Direct answer: Option A is correct. A river is not merely moving water; it is a habitat for aquatic organisms such as dolphins, fish, plants and small organisms. Understand the chain: the river provides water, dissolved oxygen, movement conditions, food and breeding places; water quality affects health; river flow affects movement, feeding and reproduction; pollution or a harmful change in flow can reduce food and injure animals. Therefore, conserving the river is necessary for dolphin-like organisms. Option A is correct because it connects both water quality and flow with life. Option B is wrong because river conditions directly support organisms. Option C is wrong because pollution usually harms aquatic life rather than always helping it. Option D is wrong because aquatic organisms need sufficiently clean water, even though different species tolerate different conditions. Exam cue: treat a river as a living habitat and link conservation with water quality, flow and food chains.