This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
Proved to be effective in the management, of Preeclampsia: 
Select and explain. 
A. Zinc, B. Calcium, C. Magnesium, D. None of the above
C: Magnesium
Answer: C: Magnesium 
Explanation: The drug of choice for control and prevention of convulsion in eclampsia is magnesium sulphate ,usually given by Pritchard&;s regime.The mechanism of action thought to have a peripheral action at the neuromuscular junction,by competing with calcium for entry into the cells.It may also have central action. TEXT BOOK OF OBSTETRICS,Sheila Balakrishnan,2nd edition,page no.268