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
Estimation of the following hormones is useful while investigating a case of gynaecomastia except 
Select and explain. 
A. Testosterone, B. Prolactin, C. Estradiol, D. Lutenizing hormone
B: Prolactin
Answer: B: Prolactin 
Explanation: None