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: Medicine
A 15-year-old boy with epilepsy on treatment with a combination of valproate and phenytoin has good control of seizures. Levels of both drugs are in the therapeutic range. All of the following adverse effects can be attributed to valproate except - 
Select and explain. 
A. Weight gain of 5 kg, B. Serum alanine aminotransaminase 150 IU/L, C. Rise in serum ammonia level by 20 g/dl, D. Lymphadenopathy
D: Lymphadenopathy
Answer: D: Lymphadenopathy 
Explanation: None