To appropriately test the functionality of the program specifically for the "2 and below" category, you need to select test data that includes ages that fall into that category, as well as data that does not, in order to ensure it recognizes the boundary correctly.
From the given options, the best choice for checking the "2 and below" category is:
0, 1, 2, 3
This selection includes ages that are within the "2 and below" range (0, 1, and 2), as well as an age that is just outside this category (3). This will help verify whether the program correctly identifies and handles the ages in the "2 and below" bracket.