Final answer:
The best response regarding concerns about the immune system of a prematurely delivered baby is that while the fetus acquires passive immunity from the mother, premature infants have less developed immune systems and may be more vulnerable to infections. However, modern healthcare provides additional measures to protect these infants.
Step-by-step explanation:
The most accurate response to the concern that a baby may not have a developed immune system if born prematurely would be b) Infants born prematurely may have deficient immunity. While it is true that a fetus acquires passive immunity through the transfer of antibodies from the mother via the placenta, these antibodies provide some level of protection after birth, it's also important to recognize that the immune system continues to develop after birth. Premature infants may have less developed immune responses and are generally more susceptible to infections compared to full-term babies due to an earlier departure from the maternally provided immune protection and underdeveloped immune systems of their own.
However, it's essential to understand that while premature infants are at increased risk for infections, modern medicine and neonatal care have made significant advancements in providing support to these vulnerable babies. In addition to the naturally acquired passive immunity and the protection from antibodies received through breast milk, healthcare providers may also administer additional treatments and precautions to protect premature infants from infections.