Nutrients Pollution
Surface Water Pollution
Oxygen Pollution
Answer: for me the best option is D.
Explanation: lets explain this.
Cellular respiration begins with a process that divides the glucose within the cells making it readily available as a source of energy. This process can occur without oxygen (anaerobic respiration) or in the presence of oxygen (aerobic respiration). Anaerobic respiration generates more excess waste (lactate) than aerobic . Besides, high levels of lactate build within the muscle cells. Excess lactate slows the cellular respiratory process and is experienced as a burning sensation in the muscles if exercise continues.
The best way to do a observation can be a microscope or by taking notes ,and by , taking pictures or, asking questions about the subject that you and the teacher or you, your teacher and the class is talking about .! Hope this helps ..