12. First successful Vaccine against cancer has been prepared for
(1) Oral cancer                                         (2) Cervical cancer
(3) Breast cancer                                      (4) Colon cancer

The first successful vaccine against cancer is for (2) Cervical cancer.

Explanation:

The earliest and most well-known cancer vaccine that has been widely successful is the Human Papillomavirus (HPV) vaccine, such as Gardasil and Cervarix. These vaccines target HPV types responsible for the vast majority of cervical cancer cases worldwide. The FDA approved Gardasil in 2006 as the first vaccine to prevent cervical cancer by protecting against HPV types 16 and 18, which cause about 70% of cervical cancers.​

Other cancer vaccines, including therapeutic vaccines for prostate cancer and melanoma, have been developed later, but the cervical cancer vaccine remains the first successful preventive cancer vaccine.