Answer:
A.Measles
Explanation:
The origin of smallpox is unknown. Smallpox is thought to date back to the Egyptian Empire around the 3rd century BCE (Before Common Era), based on a smallpox-like rash found on three mummies. The earliest written description of a disease that clearly resembles smallpox appeared in China in the 4th century CE (Common Era). Early written descriptions also appeared in India in the 7th century and in Asia Minor in the 10th century.The smallpox vaccine was the first vaccine to be developed against a contagious disease. In 1796, the British doctor Edward Jenner demonstrated that an infection with the relatively mild cowpox virus conferred immunity against the deadly smallpox virus.
