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
[{'content': 'Earliest sign of Mg toxicity: \nSelect and explain. \nA. Falling oxygen saturation on pulse oxymetry, B. Respiratory depression, C. Cardiac arrest, D. Anuria', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In case of magnesium toxicity ,there can be respirstory depression.In such cases ,infusion should be discontinued,oxygen given and 10ml of 10% calcium gluconate or calcium chloride given IV.Falling oxygen saturation in pulse oxymetry may be an early sign of magnesium toxicity TEXT BOOK OF OBSTETRICS,Sheila Balakrishnan,2nd edition,page no.269', 'role': 'assistant'}]