Once infected cells have sensed an invading pathogen, they secrete molecules called cytokines and chemokines. Cytokines such as interferons are molecules that signal neighbouring cells and induce an antiviral state in them. These cells are then primed to resist an infection with the invading virus.
Answer: A, C, and D
Explanation: The brain is basically the main nervous system, it travels down the spinal cord, and the sensory neurons are part of this system as well because nervous system in your limbs help you feel.
