The correct answer is C. Plant and animal cells require oxygen to properly break down food molecules.
Here's the breakdown of each statement:
A. Sunlight is required to break down food in plants and animals. - This statement is not true. Sunlight is required for photosynthesis in plants to create glucose, but animals do not directly use sunlight for energy conversion; they obtain energy from the food they consume.
B. The process takes place in the chloroplasts of plant and animal cells. - This is also not true. The chloroplasts are where photosynthesis occurs in plants, but animal cells do not have chloroplasts. The breakdown of food molecules occurs in the mitochondria of both plant and animal cells.
C. Plant and animal cells require oxygen to properly break down food molecules. - This statement is true for aerobic respiration, which occurs in the mitochondria of cells. Oxygen is necessary for the complete breakdown of glucose and the production of ATP, the energy currency of cells.
So, since A and B are false, while C is true, the answer is not "D. all of these." Therefore, the best answer is C.