The correct option is C Natural ecosystems include living and non living material
Ecosystem is system of interacting biotic and abiotic components and is of two types as follows: .
Natural ecosystem - This ecosystem develops by itself without human interference or support. Examples: forests, grasslands, deserts etc.
Artificial or man made ecosystem - This ecosystem is created and maintained by human beings. Examples: aquarium, pot of houseplant.
Energy transfer in any of the system is governed by second law of thermodynamics which simply states that whenever energy is transformed, there is a loss of energy through the release of heat. The functional aspects of ecosystems which facilitate interaction between biotic and abiotic components are unidirectional flow of energy and cyclic flow of matter or nutrients