From the food they intake in different ways such as Plants or other animals such as insects which are their fuel
I think the answer is B - a star! Hope this helps!
Answer:
Oxygen liberated during photosynthesis comes from the splitting or hydrolysis of water in the green plants. Cornelius van Niel experimentally proved for the first time that the oxygen liberated during photosynthesis comes from water and not from carbon dioxide.
D:Medical History because you need to know pets background to properly treat it