Answer: III.Carbon dioxide
IV.Water
The plants are the fixing agents of atmospheric carbon dioxide. Plants utilizes water and carbon dioxide in order to produce it's food in the form by the process of photosynthesis. The food produce is in the form of glucose which is a six carbon sugar. A plant takes up water from the soil. Water is necessary for photosynthesis, growth of plants and translocation of minerals to all parts of plants. Therefore, carbon dioxide and water contributes to the mass of a plant.
