The correct options are
A Calcium carbonate
B Carbon dioxide
D Water
When calcium bicarbonate is boiled, it decomposes to form an insoluble precipitate of calcium carbonate along with carbon dioxide and water. The reaction is given below:
Ca(HCO3)2boiling−−−−→CaCO3+CO2+H2O
The deposition of insoluble calcium carbonate on a surface is called scaling.