Which kingdom contains both protozoans and algae?

The Kingdom Protista is the correct answer because it is a diverse group that includes both protozoans and algae. This kingdom comprises mostly unicellular organisms, although it also includes some simple multicellular forms. Protozoans are single-celled eukaryotic organisms that can exhibit animal-like behaviors, such as movement and predation, while algae, which can be unicellular or multicellular, are primarily photosynthetic organisms that contribute significantly to oxygen production and serve as a vital part of aquatic ecosystems.

In contrast, other kingdoms listed do not include both groups. Kingdom Fungi consists mainly of fungi, which are heterotrophic and obtain nutrients through absorption, not through photosynthesis like algae. Kingdom Monera includes prokaryotic organisms, such as bacteria, which do not encompass either protozoans or algae. Kingdom Animalia is composed of multicellular, heterotrophic organisms that do not include protozoans or algae either. Therefore, Kingdom Protista is uniquely suited to contain both protozoans and algae, highlighting its role in the classification of diverse life forms.