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
A 70 years old man with prostate cancer was given radiotherapy. The recurrence of the cancer is monitored biochemically by: 
Select and explain. 
A. Androgens only, B. Prostate specific antigen and carcinoembryonic antigen, C. Prostate specific antigen only, D. ALP and CEA
C: Prostate specific antigen only
Answer: C: Prostate specific antigen only 
Explanation: Ans. c. Prostate specific antigen only