What is the domain of the following parabola?

u-shaped graph that opens down with a vertex of 1, 2

(A) x ≥ 1

(B) x ≤ 1

(C) All real numbers

(D) y ≤ 2

The domain of any function is the set of the values of x that will make the function correct. If we try to extend indefinitely the parabola with specified attributes above on the plane where it is drawn, the parabola will expand. This allows all the real numbers be the x-values. Thus, the answer is letter "C. All real numbers"