About plants: so photosynthesis produces oxygen as a waste product, but then respiration uses oxygen to produce carbon dioxide, so like doesnt that 'cancel' each other out? im confused if plants are actually helpful or not (oxygen wise)

Internal feedback works to maintain homeostasis when your a. heart rate decreases as your white blood cells increase b. breathing rate decreases as your red blood cells decrease c. heart rate increases as your liver is cleaning blood d. breathing rate increases as your heart rate increases