Read the passage carefully and give the answer of 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.
People hastened to get themselves vaccinated because

Options

A. many doctors supported Jenner's claims
B. fear of the terrible disease drove them to take the risk of vaccination
C. supplies of pure vaccine had now become available
D. the practice of vaccinating had spread all over the world