The correct answer is: A. Environment
The term “eco” comes from the Greek word “oikos”, which means “house” or “dwelling place”. In the context of environmental science, “eco” refers to the natural world, including all living things and their interactions with each other and with the physical environment.
Option B, “ecotone”, is a transitional area between two different ecosystems. For example, a forest edge is an ecotone between the forest and the open field.
Option C, “ecotourism”, is a type of tourism that focuses on the natural environment and the conservation of natural resources.
Option D, “soil”, is the loose material on the surface of the Earth that supports plant growth.
I hope this helps! Let me know if you have any other questions.