Correct Answer: class

Solution : The correct option is class .

Concerning taxonomic categories, the term "Mammalia" is a class. In the hierarchical classification system, living organisms are grouped into a series of taxonomic ranks and "Mammalia" is one of these ranks at the class level. The class Mammalia includes animals that are characterized by mammary glands, hair or fur and a warm-blooded metabolism. Humans, dogs, cats, whales and bats are examples of organisms classified within the class Mammalia.