Set A has an average of 2.
To find the average of the sets individually, we add the total number of blocks up then divide it by the number of groups. Set A can be solved like so:
4 + 1 + 1 = 6
6 / 3 = 2
Set A has an average of 2.
Now to solve for set B:
4 + 2 = 6
6 / 2 = 3
Set B has an average of 3.
Therefore, option A has an average of 2 and is correct.