**Core Concept**
The zero dose of polio vaccine is administered at birth, as part of the strategy to eradicate poliomyelitis. This dose is crucial for providing early protection against poliovirus infection, especially in areas with high transmission rates.

**Why the Correct Answer is Right**
The zero dose of polio vaccine is given at birth, typically within the first 24 hours of life, to provide immediate immunity against poliovirus. This dose is often administered as part of the oral poliovirus vaccine (OPV) or inactivated poliovirus vaccine (IPV), depending on the regional vaccination policy. The early administration of the zero dose helps to prevent poliovirus infection, which can be severe and lead to long-term neurological sequelae.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the first dose of poliovirus vaccine is indeed given at birth, not the first dose of a different vaccine.
**Option B:** This option is incorrect because the first dose of rotavirus vaccine is given at 6-14 weeks of age, not at birth.
**Option C:** This option is incorrect because the first dose of Hib vaccine is given at 2 months of age, not at birth.
**Option D:** This option is incorrect because the first dose of Hepatitis B vaccine is given at birth, but it is not the same as the zero dose of poliovirus vaccine.

**Clinical Pearl / High-Yield Fact**
The zero dose of polio vaccine is a critical component of global efforts to eradicate poliomyelitis. Administering this dose at birth helps to prevent poliovirus infection and its associated complications, making it an essential part of newborn vaccination protocols.

**Correct Answer: A.**