As to CNS-targeted drug delivery, which of the following statements is NOT TRUE? A. Blood brain barrier make the brain inaccessible to CNS-targeted drugs in the systemic circulation. B. Low-molecular and lipid-soluble drugs can rapidly cross blood brain barrier by passive diffusion. C. It is more difficult to deliver biotherapeutics across blood brain barrier. D. Increasing the hydrophilicity of a drug molecule is likely to increase its transport across the BBB.