This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Absence of lymph nodes is characteristic of 
Select and explain. 
A. Brain, B. Liver, C. Lung, D. Placenta
A: Brain
Answer: A: Brain 
Explanation: The brain, pa of the central nervous system, has blood vessels but has been thought to lack lymphatic vessels, as they've never been found in humans . Ref - researchgate.net