Which of the following statements about protists is true?

• A. Protists form a monophyletic group.
• B. Protists are classified as prokaryotes.
• C. Protists are a diverse group of mostly unicellular eukaryotic organisms.
• D. All protists are photosynthetic.

Answer: (C)

Verified step by step guidance

1. Step 1: Begin by understanding the term 'protists.' Protists are a diverse group of mostly unicellular eukaryotic organisms, meaning they have a nucleus and membrane-bound organelles, unlike prokaryotes.
2. Step 2: Evaluate the first statement: 'Protists form a monophyletic group.' A monophyletic group includes all descendants of a common ancestor. Protists do not form a monophyletic group because they are highly diverse and include organisms that do not share a single common ancestor. This statement is false.
3. Step 3: Evaluate the second statement: 'Protists are classified as prokaryotes.' Prokaryotes lack a nucleus and membrane-bound organelles, while protists are eukaryotic. Therefore, this statement is false.
4. Step 4: Evaluate the third statement: 'Protists are a diverse group of mostly unicellular eukaryotic organisms.' This is true because protists include a wide variety of organisms, most of which are unicellular and eukaryotic, though some are multicellular.
5. Step 5: Evaluate the fourth statement: 'All protists are photosynthetic.' This is false because not all protists are photosynthetic. Some protists, like amoebas, are heterotrophic and obtain energy by consuming other organisms.