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: Gynaecology & Obstetrics
In a woman presenting with amenorrhea headache, blurred vision and galactorrhea appropriate investigation: 
Select and explain. 
A. Prolactin levels, B. LH, C. FSH, D. HCG
A: Prolactin levels
Answer: A: Prolactin levels 
Explanation: A women presenting with headache, blurred vision and galactorrhea raises of a pituitary prolactinoma and so appropriate investigation would be:

S prolactin (most important)
TSH (as patients with hypothyroidism have elevated TRH which acts to stimulate the release of prolactin)
X ray skull (shows space occupying lesion)
MRI
Contrast enhanced CT