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: Pharmacology
Which of the following drugs cause oligospermia ? 
Select and explain. 
A. Leflunomide, B. D - Penicillamine, C. Methotrexate, D. Sulfasalazine
D: Sulfasalazine
Answer: D: Sulfasalazine 
Explanation: Sulfasalazine can cause a reversible infertility in males owing to changes in sperm number and morphology.