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
Mechanism of action of tamoxifen is: 
Select and explain. 
A. Has androgenic receptor blocking action, B. Inhibits enzyme 5α-reductase, C. Has partial agonist and antagonist action on estrogen receptors, D. Inhibition of FSH and LH release from the pituitary
C: Has partial agonist and antagonist action on estrogen receptors
Answer: C: Has partial agonist and antagonist action on estrogen receptors 
Explanation: None