The correct option is B. Species. Explanation of the Correct Answer In biological classification, organisms are grouped into hierarchical categories based on shared characteristics. This system is known as taxonomy, and it organizes living things into a series of ranks. The main ranks, from the broadest to the most specific, are:

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species

Among these categories, species is the most specific and lowest rank. A species is defined as a group of organisms that can interbreed and produce fertile offspring under natural conditions. For example, the domestic cat is classified as Felis catus, where Felis is the genus and catus is the species. Why the Other Options Are Incorrect Now, let’s examine why the other options are not the correct answer:

• A. Class: This is a higher taxonomic rank that groups together multiple orders. For example, the class Mammalia includes all mammals, which encompasses various orders such as Carnivora (dogs, cats) and Primates (monkeys, humans). Since class is broader and includes many different organisms, it cannot be the lowest category.
• C. Family: This rank is also higher than species and groups together multiple genera (plural of genus). For instance, the family Felidae includes all cats, such as lions (Panthera leo), tigers (Panthera tigris), and domestic cats (Felis catus). Like class, family encompasses a wider range of organisms, making it a higher category than species.
• D. Order: This rank is even broader than family and includes multiple families. For example, the order Carnivora includes families like Felidae (cats) and Canidae (dogs). Since order is a higher classification level, it cannot be the lowest category.

Summary of Key Points

• Species is the most specific and lowest category in the biological classification hierarchy.
• Higher categories include class, family, and order, which group together multiple organisms based on shared characteristics.
• Understanding the hierarchy of classification helps in identifying and categorizing organisms accurately.

Revision Summary

• The lowest category of classification is species.
• Taxonomic hierarchy includes: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.
• Each rank groups organisms based on shared traits, with species being the most specific.
• Higher categories (class, family, order) encompass broader groups of organisms.