A qualitative variable is the type of variable that can't be numerically expressed but can be categorized. The colors of the leaves on a branch can be categorized as green, yellow and orange etc. Thus, the colors of the leaves is a qualitative variable. So, the correct option is C.
Notice how the input 5 leads to the output 3 when we look at the S(x) function. The inverse will undo this. So that must mean the answer is choice A where we have the input 3 lead to the output 5. In short, the inputs and outputs swap places. This means the domain and ranges swap.
