What is the domain of this function?

Answer:
B {1, 2, 3, 4} is the right answer
Skills needed: Domain vs Range, Set Values
Step-by-step explanation:
1) Each function has an input and output
2) The inputs are the x-values, and the outputs are the y-values
3) Here, the domain is the x-values (on the left side)
They are:
1
2
3
4
Which means the domain is {1, 2, 3, 4} ---> This is option B