Well, plants go through a phase Called photosynthesis. They take in sunlight, carbon dioxide (our exhale), and water to make sugar. Sugar is their supply of food, and the waste they make. It's oxygen (what we inhale)
number 8 is b because when you eat plants or animals, it get transfred to glucose which is then transfered to atp. Think about it this way, when you are sick, you dont just go outside in the sun to recharge and then you suddenly get better, and energy, you have to rest and eat certain foods that will restore your ATP levles.
That would be the independent variable :)
