Answer:
Weather conditions
Explanation:
Food can be limited based on location, however, scientists can control what kind of food it is. Soil can be tested and experimented on. There can be a lot of it and different kinds. Space is fought over because of territories and is limited compared to how many people and animals there are. Weather is not something that can be controlled in an experiment since it is sporadic.
Could you attach the statements so i can answer :)
Answer:
The waste products of one are what the other needs to preform and make enegery and they both make energy
Explanation:
Maybe changing the experiment up in a different way? So they can see what way works better
Your answer is D. Hope this helps!