This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Lymphocytes are located in each of the following tissues or organs EXCEPT one. The one exception is - 
Select and explain. 
A. Brain, B. Spleen, C. Lymph nodes, D. Thymus gland
A: Brain
Answer: A: Brain 
Explanation: None