The correct answer is D. River
Step-by-step explanation:
Rivers are one of the most common ecosystems. A river is characterized by flowing water in which biotic factors (animals, plants, bacteria, etc.) and abiotic factors (rocks, water, minerals) interact. Also, they cross major ecosystems such as forests or rainforests.
Moreover, rivers are unique because they contain fresh rather than salt water as in the ocean, and they are always flowing while in a marsh, swamp or lake the water does not flow. This suggests the ecosystem is the photograph is a river because in this the water flows and as a result of this, there is a strong current which is possible in a river but not in a lake, marsh or swamp.