Cell organelle that stores materials such as water, salts, proteins, and carbohydrates.

• A. Chloroplast
• B. Endoplasmic Reticulum
• C. Nucleolus
• D. Vacuole

Answer: (D)

Storage in cells is handled by vacuoles, which are membrane-bound sacs that hold water, salts, nutrients, and other substances. This organelle is especially prominent in plant cells as a large central vacuole that helps maintain turgor pressure by keeping water inside the cell, and it can store carbohydrates, proteins, and ions as well. Chloroplasts store energy as sugars through photosynthesis, the endoplasmic reticulum is involved in making and transporting proteins and lipids, and the nucleolus is where ribosomes are assembled inside the nucleus. Because the description emphasizes a storage role for water, salts, proteins, and carbohydrates, the vacuole is the best fit.