Which is an example of an epidemic? a) whooping cough b) obesity c) black death d) spanish flu

What is a small pants but the m word mean my friends call me that a lot im 5 year old

In multiple sclerosis, the immune system destroys the substance that coats and protects nerve fibers in the brain and spinal cord. this causes inflammation and injury to the nerves, and the axons don't conduct impulses as well.

Can someone give me one specific health problem, and explain it. !