The correct answer is option 3, Chlorophyll. Chlorophyll is a molecule found in plants that is comparable to hemoglobin in animals. Hemoglobin is responsible for carrying oxygen in the blood of animals, while chlorophyll plays a crucial role in photosynthesis, the process by which plants convert sunlight into energy. Chlorophyll is responsible for capturing light energy and using it to convert carbon dioxide and water into glucose, which is the primary source of energy for plants. It gives plants their green color and is found in the chloroplasts of plant cells. Cytochrome, option 1, is a protein involved in cellular respiration. Cellulose, option 2, is a complex carbohydrate that makes up the cell walls of plants. Carotene, option 4, is a pigment found in carrots and other vegetables.