Answer:
Answer is option A.
Ecotones are the transitional zones between ecosystems.
Step-by-step explanation:
Ecotones are regions that form a boundary (transition) between two ecosystems or biomes. The meeting and integration of two biological communities in an ecotone result in increased biodiversity. As a result of the influence between two biological communities, a greater number of various species and a higher density of organisms can be found in an ecotone, which is known as the edge effect.
Ecotone has an important role in the environment as it functions as a habitat of greater genetic diversity. It acts as a bridge between ecosystems and causes gene flow from one population to another. It also protects the neighboring ecosystem from damage such as pollution.
Usually, ecotones are formed naturally, but they are also created through the result of human interaction such as deforestation, irrigation, etc. Ectones can be narrow or wide and local or regional. Examples of ectones include grasslands - the area between forest and desert such as the transition zone between Arctic Tundra and Forest biomes in Northern Siberia, mangrove forests - the area between terrestrial and marine ecosystems, marshlands - the area between wet (river) and dry (riverbank) ecosystems, estuaries - the area between two wet ecosystems, etc.