The answer is letter C.
Encephalitis is a disease in which the brain swells causing edema and eventually the destruction of nerve cells within the brain. It is a very rare condition that often occurs in the year of life but it eventually decreases with age. Older adults and very young groups are most likely to have a severe case of encephalitis. This disease is often caused by a viral infection that can occur through contaminated food, mosquito or insect bites, breathing in contaminated air, and possibly skin contact.