________ are a diverse collection of mostly single-celled eukaryotes, which are sorted into several kingdoms to reflect their evolutionary relationships.

• A. Bacteria
• B. Protists
• C. Archaea
• D. Plantae

Answer: (B)

Protists are a broad, diverse collection of mostly single-celled eukaryotes that biologists place into several kingdoms to reflect their evolutionary relationships. They include organisms like amoebas, paramecia, and many algae, spanning a wide range of lifestyles and nutritional modes. Because this group is so varied, scientists historically grouped them into a single kingdom called Protista, but modern classifications often split these lineages into multiple kingdoms or clades to better reflect how they are related. Bacteria and Archaea are prokaryotes, lacking a true nucleus, so they don’t fit this description. Plantae are multicellular and typically photosynthetic, which also doesn’t match the mostly single-celled protist description.