The correct answer is D. Food that the animal has eaten and changed into other organic compounds.
Explanation:
Different from plants, that use water, carbon dioxide, and sunlight to create organic compounds and obtain energy, animals need to consume food that depending on the animal includes plants, other animals or both. Additionally, once an animal consumes food this is digested by specialized organs and cells and changed into organic compounds, this includes carbohydrates, lipids, protein, and nucleic acids that are necessary for organisms to obtain energy, grow and live. According to this, as an animal grows its mass increases, and the matter that makes up this new mass comes mostly from food the animal eats and changes into organic compounds (Option D).