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: Skin
25 yr old male having fever & malaise since 2 weeks, ahritis of ankle joint and tender erytematous nodules over the shin. Diagnosis is: 
Select and explain. 
A. Erythema nodosum, B. Hansen'sdisease, C. Weber- Christian disease, D. Nodular Vasculitis
A: Erythema nodosum
Answer: A: Erythema nodosum 
Explanation: A i.e. Erythema nodosum