When 22.2 g of a soluble ionic compound (formula weight=111 g/mol) are added to 1.0 kg of water (Kf=1.86 C/m), the freezing point of the resulting solution is -1.12 C. Which of the following could be the general formula of the ionic compound?
A. MX
B. MX2
C. MX3
D. M2X3