This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
Which of the following is not permeable through the Blood Brain Barrier? 
Select and explain. 
A. Water, B. Lipophilic drugs, C. Gas, D. Proteins
D: Proteins
Answer: D: Proteins 
Explanation: Large molecules do not pass through the BBB easily. Low lipid (fat) soluble molecules do not penetrate into the brain. However, lipid soluble molecules, such as barbituate drugs, rapidly cross through into the brain. Molecules that have a high electrical charge are slowed. Ref: guyton and hall textbook of medical physiology 12 edition page number:672,673,674