Which of the Following Molecules Contain Both Covalent and Ionic

Multiple Choice

Which of the following molecules contain both covalent and ionic bonds? $$\begin{array} { c c c c } \mathrm { NaCl } & \mathrm { NH } _ { 4 } \mathrm { OH } & \mathrm { CH } _ { 3 } \mathrm { OH } & \mathrm { MgCO } _ { 3 } \\\text { I } & \text { II } & \text { III } & \text { IV }\end{array}$$

A) I, II
B) I, IV
C) II, III
D) II, IV