Read the passage carefully and answer the question given below. Many doctors flatly refused to believe Jenner when he announced that he had found a preventive against smallpox. They declared vaccination to be a dangerous practice. But the dread of smallpox was in everybody's heart, and people flocked to Jenner to be vaccinated. The Latin word for cow is 'vacca', it is the root from which the word vaccination was formed, Some of the vacca' used by Jenner were not pure and some harms were done, but when supplies of pure vaccine were available, the practice of vaccinating spread all over England and from England to other countries. We hardly hear of outbreaks of smallpox now.
The passage describes

Options

A. how smallpox may be treated
B. how vaccines were manufac tured in England
C. the dangers of vaccination especially for children
D. the gradual acceptance of vaccination as a preventive against smallpox