Answer: {-3, 0, 1, 9}
Explanation:
We can think of a function as a "machine" that "eats" an input, and it transforms it into an "output". A more theoretical definition of a function is a relationship that maps elements of a given set (the domain, this is the set of the inputs) into only one element from another set (the range, this is the set of the outputs)
In the image, we can see that the elements {-3, 0, 1, 9} are mapped into the element {2}
Then the set of the inputs will be the set {-3, 0, 1, 9}
The correct option is the last one.