it's kinda blurry...I can hardly see but I'll try n answer
Oxygen is used for breathing
Chlorine is used for purifying water
Nitrogen is used for plants
Potassium is used in fertilizer
Answer: Central Nervous System
Explanation:
The emotions such as pain, happiness, trauma and other sensory things are controlled by the brain. The things that we feel like pain, heat, cold et cetera are also controlled by the brain.
The nervous system has two parts peripheral nervous system and the central nervous system. The pain signals are carried from the knees to the brain by the central nervous system.