A Group of Nursing Students Asks a Nurse to Explain

A group of nursing students asks a nurse to explain the blood-brain barrier. The nurse would be correct to say that the blood-brain barrier:

A) prevents some potentially toxic substances from crossing into the central nervous system.
B) causes infants to be less sensitive to CNS drugs and thus require larger doses.
C) allows only ionized or protein-bound drugs to cross into the central nervous system.
D) prevents lipid-soluble drugs from entering the central nervous system.