Answer:
The answer is B.
Explanation:
A is incorrect because B is correct (plants are autotrophs).
C is incorrect because the first stage of cellular respiration is glycolysis, and the second is the Krebs cycle, neither of which require oxygen.
D is incorrect because cells take in oxygen to perform cellular respiration. Carbon dioxide is the product.
Algae make energy or food is through the process of photosynthesis. Photosynthesis involves the use of sunlight to synthesize carbon dioxide and water to make raw carbohydrates, which is their source of energy.
Vestigial because they don't use it but it's still there