Answer:
Domain: All real numbers
C is correct
Explanation:
We are given a graph of parabola because it is U-shape with vertex (1,2) and open downwards.
Open downwards parabola equation:

We need to find the domain of graph.
As we know the domain of parabola is all real number but restriction on range.
Domain: All real numbers

Hence, The domain of given graph is all real numbers.