What is the function of a vacuole in a plant cell?

A vacuole in a plant cell primarily serves the function of maintaining cell shape and providing structural support. This is crucial for plant cells, which rely on the pressure exerted by the vacuole, filled with cell sap, to keep the cell turgid. When the vacuole is full of fluid, it pushes against the cell wall, helping to maintain the cell's shape and overall rigidity. This pressure is essential for many physiological processes in plants, including growth and nutrient storage.

While photosynthesis and energy production are vital cellular processes, they occur in chloroplasts and mitochondria, respectively. Protein synthesis occurs in ribosomes. Therefore, option C accurately reflects the key role of vacuoles in providing structural integrity to plant cells, distinguishing it from the other choices related to different cellular functions.