**Core Concept**
A preterm infant's immune system is immature, and their response to vaccines may be altered. The decision to administer vaccines to preterm infants is based on their birth weight and gestational age.

**Why the Correct Answer is Right**
Preterm infants with a birth weight of 1600 grams are considered at risk for immune system dysfunction and may not respond adequately to vaccines. The BCG vaccine is a live attenuated vaccine that can cause significant illness in immunocompromised individuals, including preterm infants. Administering the BCG vaccine to a preterm infant with a birth weight of 1600 grams may increase the risk of severe adverse reactions.

**Why Each Wrong Option is Incorrect**
* **Option A:** Hepatitis B vaccine is a recombinant vaccine that is safe for administration to preterm infants, regardless of birth weight.
* **Option B:** OPV (Oral Poliovirus Vaccine) is a live attenuated vaccine, but it is generally recommended for administration to preterm infants, especially in areas where polio is endemic.
* **Option C:** There is no specific contraindication to administering the Rotavirus vaccine to preterm infants with a birth weight of 1600 grams.

**Clinical Pearl / High-Yield Fact**
Preterm infants with a birth weight of less than 2000 grams should not receive live attenuated vaccines, such as BCG, OPV, or Rotavirus, due to their increased risk of adverse reactions.

**Correct Answer:** B.