Which of the following is an example of a live vaccine?

Correct option is B

The Measles vaccine is a live attenuated vaccine, meaning it contains a weakened form of the live virus that cannot cause disease in healthy individuals but still stimulates a strong immune response. It is often administered as part of the MMR (Measles, Mumps, Rubella) vaccine and provides long-term immunity.
Explanation of options: (a) Hepatitis B – This is a recombinant vaccine made using genetic engineering; it does not contain live virus. (b) Measles – This is the correct answer. It is a live attenuated virus vaccine, used widely in childhood immunization programs. (c) Influenza – Typically available as an inactivated or subunit vaccine; only the nasal spray version is live attenuated, but not commonly used. (d) Rabies – The commonly used rabies vaccines are inactivated (killed) vaccines, not live attenuated ones.