As shown in the figure, it is a cuboid with a length of 3 cm and a width of 2 cm. Dig out a small cube with a side length of 1 cm, and its surface area is ().

According to the meaning of the title and the figure, after digging out a small cube with a side length of 1 cm, the surface area is reduced by two sides, that is, two square centimeters;

However, its surface has increased by four sides at the same time, that is, by four square centimeters;

So its surface area has increased by 2 square centimeters.

So choose: a.