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
40-year-old men are suffering from fever & pain in the scrotum which is not relieved by elevation of the testis. 3 days before had sexual contact with a young female - 
Select and explain. 
A. Testicular tumour, B. Acute epididymitis, C. Torsion of testis, D. Acute orchitis
C: Torsion of testis
Answer: C: Torsion of testis 
Explanation: Torsion of testis can be differentiated from acute epididymitis by Prehn's sign. ie

On the elevation of testis the pain increases in → Torsion
On the elevation of the testis, the pain decreases in → epididymoorchitis.
Don’t be confused with fever, it can also occur in torsion, especially in older patients.