For this case we have that by definition, the domain of a function is given by the set of all the possible input values of the function. That is, the values that the variable "x" takes.
Also, it can be said that it is the set of all the values for which the function is defined.
The table shows that "x" takes the following values:
{3,4,5,6}
Answer:
Domain: {3,4,5,6}
Option C