A 10.0 g sample of a mixture of `CaCl_2` and `NaCl` is treated to precipitate all the calcium as calcium carbonate. Thus `CaCO_3` is heated to convert all the Ca to CaO and the final mass of CaO is 1.62 g. What is the percentage by mass of `CaCl_2` in the original mixture?
A. 0.152
B. 0.321
C. 0.218
D. 0.1107