A. magnesium carbonate
B. magnesium and potassium chloride
C. magnesium calcium carbonate
This question was addressed to me in an internship interview.
This interesting question is from Processes of Magnesium and its Alloys in section Magnesium Alloys of Aerospace Materials & Processes
The explanation is: Magnesium can be found commonly in various ores across the world. Dolomite is a magnesium calcium carbonate. Magnesium carbonate is magnesite. Carnallite is magnesium and potassium chloride.