Answer:
Oxygen
Explanation:
The formula for cellular respiration is oxygen + glucose -> water, carbon dioxide, energy. You can already cross out A and D because they aren't in the formula, so you have two left, water and oxygen. The reason why it is oxygen and not water is because without oxygen you can't even have water. also, I just got this right on my test :-)
The answer should be the first quarter moon
Free-living flat worms = carnivores or scavengers
Have digestive cavity, mouth, pharynx
Parasitic Flatworms: = Feed on blood, tissue fluids, or pieces of cells from within a host
The variable “x” should go on the x-axis
