Answer: C. male elk fighting over a female.
An ecosystem is a biotic community. It exhibit two components named as biotic and abiotic factors. Examples of abiotic (non-living) factors includes water, soil, temperature, sunlight and others. Biotic (living) factors includes all living species such as plants, animals, microbes and humans.The interaction of abiotic factors and biotic factors facilitate life on earth.
A male elk fighting over a female is an interaction between living organisms. It does not show interaction between biotic and abiotic factors of ecosystem.