According to research, the closest living relative of animals is a flagellated protist called a(n):

• A. paramecium
• B. euglena
• C. choanoflagellate
• D. dinoflagellate

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the context of the question. The problem is asking about the closest living relative of animals, which requires knowledge of evolutionary biology and the relationships between different organisms.
2. Step 2: Recall that animals are part of the domain Eukarya, and their closest relatives are also eukaryotic organisms. Specifically, protists are a diverse group of eukaryotes that include some species closely related to animals.
3. Step 3: Learn about choanoflagellates. Choanoflagellates are flagellated protists characterized by a collar-like structure surrounding their flagella. This structure is similar to the choanocytes found in sponges, which are simple animals, suggesting a close evolutionary relationship.
4. Step 4: Compare choanoflagellates to other protists listed in the options. Paramecium and euglena are protists but do not share the specific structural or genetic similarities with animals that choanoflagellates do. Dinoflagellates are primarily associated with marine ecosystems and are not closely related to animals.
5. Step 5: Conclude that choanoflagellates are the correct answer based on their structural and genetic similarities to animals, as supported by evolutionary research.