Which sentence is most likely the main idea in a paragraph about why plants need sunlight?

• A. Plants can grow best in darkness.
• B. Sunlight is not necessary for plant life.
• C. Plants need sunlight to make food through photosynthesis, which supports their growth.
• D. Water is the only necessity for plants.

Answer: (C)

Sunlight provides the energy plants need to make their own food through photosynthesis. This explains why light is essential: the process uses light energy to convert carbon dioxide and water into glucose, a sugar that powers growth and life processes in the plant. When a paragraph discusses why plants need sunlight, this idea—the connection between light energy, food production, and growth—best captures the main point. The other statements misrepresent plant needs: some claim darkness is best, some say sunlight isn’t necessary, and others say water is the only requirement; none of these explain how light enables plants to produce food and grow.