Which statement best captures the main idea of a paragraph about why plants need sunlight?

• A. Water is more important than sunlight for growth.
• B. Sunlight helps plants to grow by making food through photosynthesis.
• C. Plants can grow without sunlight if watered.
• D. Sunlight has no effect on photosynthesis.

Answer: (B)

Sunlight provides the energy plants need to make their own food through photosynthesis. In this process, the plant’s chlorophyll captures light and uses it to convert carbon dioxide and water into glucose, the sugar that fuels growth, while releasing oxygen. So the main point is that sunlight is essential because it powers the creation of food that drives growth.

Water is necessary for life, but it doesn’t by itself create the food plants need. Without light, photosynthesis can’t occur, so growth would slow or stop. Saying sunlight has no effect on photosynthesis is incorrect, since light directly drives the chemical reactions that produce plant food.