Which of the following is a characteristic of a mixture

I believe you forgot to add the choices. I will tell you some of the characteristics of mixtures and I hope you find one of them in the choices you have.

A mixture is a physical combination between two or more elements. No chemical reaction is involved in the formation of mixtures.
The components of the mixture can be separated using physical methods such as filtration, boiling and condensation.
Examples of mixtures include mixture of sugar and water or mixture of salt and sugar.

  soil is  vegetal. in forest or prairies, as well as agricultural fields, dead plants are transformed by different kinds of living organisms. 

Answer a, i don't feel like going into detail on this one because of how long that read was. water goes whoosh moving through the turbines to turn them and convert the energy of these mechanisms into electrical energy :