Among those shown below, which is the smallest permitted to contain one three-way switch, an external type MC connector, and one 12 AWG ground? Only one cable enters the box and all conductors connect to the switch.
a. 2.75" deep switch box
b. 2\frac{5}{8}" deep device box
c. 1\frac{1}{4}" deep 4"-SQ with 2.2 in$^3$ p-ring
d. 3\frac{1}{2}" deep masonry box