Answer:
The correct answer is letter C.
C because we are testing the effectiveness of Fertilizer X and Y and using no fertilizer can help determine if that would be better than using a fertilizer. Additionally, a control group of no fertilizer would be the third plant as that is considered normal for the experiment. Msg me for any more questions
Answer:
Respiration begins at the nose or mouth, where oxygenated air is brought in before moving down the pharynx, larynx, and the trachea. The trachea branches into two bronchi, each leading into a lung. Each bronchus divides into smaller bronchi, and again into even smaller tubes called bronchioles.
I would say extreme temperatures.