Number of carbonyl compounds in the following that undergo Cannizzaro reaction are :
$$\begin{gathered} \mathrm{A}. \mathrm{PhCHO} \\ \mathrm{B}. \mathrm{HCHO} \\ \mathrm{C}. {\mathrm{CCl}}_3\mathrm{CHO} \\ \mathrm{D}. {\left({\mathrm{CH}}_3\right)}_3\mathrm{C}-\mathrm{CHO} \end{gathered}$$

Carbonyl compounds having no α−hydrogen will undergo Cannizzaro reaction. 

Out of the above-given options, A, B and D none of them have alpha hydrogen. So, all can undergo Cannizzaro reaction.