Which term denotes the first level of classification in biological hierarchy?

The term that denotes the first level of classification in the biological hierarchy is "Domain." However, in the context of the provided choices, the correct term for the first level of classification is not included. The classification hierarchy typically starts with Domain as the broadest category, followed by Kingdom, Phylum, Class, Order, Family, Genus, and Species.

While "Primary" could imply a first-level classification in a general sense, it is not an official term used in biological classification. The other options—Secondary, Tertiary, and Quaternary—refer to further levels of classification or hierarchical organization, but they do not accurately represent the first level in the established biological taxonomy framework.

Understanding the correct hierarchy is essential in biology because it helps scientists categorize and communicate about the vast diversity of life on Earth effectively. The correct classification system assists in studying evolutionary relationships and biological functions among organisms.