Explanation:

The green color of leaves is primarily due to the presence of Chloroplasts (Option C), which are organelles containing the green pigment chlorophyll. Chlorophyll is essential for photosynthesis, the process by which plants convert light energy into chemical energy. Chromoplasts (Option A) contain pigments responsible for colors other than green (e.g., red, yellow, orange). Leucoplasts (Option B) are colorless plastids involved in storage. Tonoplast (Option D) is the membrane surrounding the plant cell's central vacuole.