The range of a function is the set of y-values the function contains. Thus, in this case, the range would be the set of values under the y column, as this represents the y-values the function produces.
We see "2, 3, 4, 2" under the y column. Since we are establishing a set of values, we are going include all the values under the column, which includes 2, 3, and 4. We are not going to repeat the second 2 because it isn't necessary, as 2 is already in the set thus.
Thus, the final set for the range of the function is {2, 3, 4}, or Choice A.