Answer: Contractile vacuole.
- A Mitochondria
- B Contractile vacuole
- C Ribosome
- D Nucleus
Correct answer: B. Contractile vacuole
Explanation: Contractile vacuole in Amoeba and other protists pumps out excess water, maintaining osmotic balance.
Animal cell structure with major organelles labeled. Image: LadyofHats (Mariana Ruiz), Public Domain, via Wikimedia Commons.
Concept context
Cell theory, prokaryotic vs eukaryotic cells, organelles and their functions. Foundation of all biology.