Answer:
The correct answer is: mutualism
Explanation:
Mutualism refers to a relationship between two organisms, where both organisms benefit from the association. In this instance, the relationship between cellulose-digesting microorganisms and their hosts- termites and ruminant mammals- is characterized by mutualism because both organism benefit from their association. The microorganisms benefit by getting their nutrition from the cellulose in guts of their hosts. Whereas, the hosts benefit from the cellulose-digesting microorganisms by getting help in digesting the cellulose they consume in their diet.
D. A protein catalyst in a living organism
The most recent and arguably best-known, the Cretaceous–Paleogene extinction event, which occurred approximately 66 Ma (million years ago), was a large-scale mass extinction of animal and plant species in a geologically short period of time.