**Core Concept**
BCG (Bacillus Calmette-Guerin) vaccine is a live attenuated vaccine used to protect against tuberculosis (TB) infection. It is known to cause local reactions and complications at the site of injection, primarily due to the live bacteria.

**Why the Correct Answer is Right**
The BCG vaccine is associated with complications such as regional lymphadenitis, abscess formation, and, rarely, otitis and osteomyelitis. This occurs due to the spread of the attenuated bacteria from the site of injection to the surrounding tissues, including the ear and bone. The risk of complications is higher in individuals with compromised immune systems, but it can also occur in healthy individuals.

**Why Each Wrong Option is Incorrect**
* **Option A:** Hepatitis B vaccine is a recombinant vaccine that does not cause live bacteria-related complications like BCG. It is primarily associated with local reactions such as pain, redness, and swelling at the injection site.
* **Option C:** Measles vaccine is a live attenuated vaccine, but it is not associated with otitis and osteomyelitis. Measles vaccine complications are more commonly related to fever, rash, and upper respiratory tract infections.
* **Option D:** IPV (Inactivated Poliovirus Vaccine) is an inactivated vaccine that does not contain live bacteria or viruses. It is not associated with complications such as otitis and osteomyelitis.

**Clinical Pearl / High-Yield Fact**
BCG vaccine complications can be minimized by using proper vaccine administration techniques, including proper needle insertion, correct dose, and avoidance of intradermal injection. Healthcare providers should be aware of the potential risks and monitor patients for signs of complications after BCG vaccination.

**✓ Correct Answer: B. BCG**