This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S., Subject name: Medicine
Myasthenia gravis may be associated with: 
Select and explain. 
A. Drug intake, B. Viral infection, C. B lymphocyte dysfunction, D. Thymoma
D: Thymoma
Answer: D: Thymoma 
Explanation: Ans: dRef: Harrison, 16thed, p. 2521, Table 366.3