The Animal Kingdom encompasses both vertebrates (animals with a backbone) and invertebrates (animals without a backbone). This kingdom is characterized by multicellular, heterotrophic organisms that can move and engage in sexual reproduction.

The correct answer is option 'B', the Animal Kingdom.

The Animal Kingdom is a taxonomic kingdom that encompasses both vertebrates and invertebrates. It is one of the five kingdoms in the classification system developed by Carl Linnaeus.

Here is an explanation of why the Animal Kingdom includes both vertebrates and invertebrates:

1. Definition of the Animal Kingdom:
- The Animal Kingdom, also known as Animalia, is a diverse group of organisms that are multicellular, eukaryotic, and heterotrophic.
- Heterotrophic means that animals obtain their nutrition by consuming organic matter, either by eating other organisms or by consuming organic material in their environment.

2. Classification of Animals:
- Animals are classified into various groups based on their characteristics and evolutionary relationships.
- The highest level of classification in the Animal Kingdom is the kingdom itself, Animalia.
- Within the Animal Kingdom, animals are further classified into different phyla, classes, orders, families, genera, and species.

3. Vertebrates and Invertebrates:
- Vertebrates are animals that have a backbone or vertebral column. This includes animals such as mammals, birds, reptiles, amphibians, and fish.
- Invertebrates, on the other hand, are animals that do not have a backbone. This includes a vast majority of animal species, such as insects, spiders, worms, mollusks, and crustaceans.

4. Diversity in the Animal Kingdom:
- The Animal Kingdom is incredibly diverse, with over 1.3 million known species.
- Vertebrates make up only a small fraction of this diversity, with around 65,000 described species.
- Invertebrates account for the majority of animal species, with estimates ranging from 97% to 99% of all known animal species.

5. Importance of the Animal Kingdom:
- The Animal Kingdom is essential for maintaining ecological balance and biodiversity on Earth.
- Animals play various roles in ecosystems, including as predators, prey, pollinators, decomposers, and nutrient recyclers.
- Many animals also have significant economic and cultural importance for humans, such as livestock for food, pets, and sources of inspiration for art and literature.

In conclusion, the Animal Kingdom encompasses both vertebrates and invertebrates. This diverse group of organisms plays a crucial role in ecosystems and has significant importance for human society.