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: Surgery
Which system is primarily affected by tetanus? 
Select and explain. 
A. Hematological, B. Nervous, C. Skeletal, D. All
B: Nervous
Answer: B: Nervous 
Explanation: Nervous REF: Harrison's Internal Medicine 17th edition chapter 133 "Tetanus is a neurologic disorder, characterized by increased muscle tone and spasms that is caused by tetanospasmin, a powerful protein toxin elaborated by Clostridium tetani"