Hello!
First, let me show you the graph of the function f(x) = x²:
The exercise informs that this graph was shifted 3 units down. It means that the parabola must be the same, it just has to pass the y-axis at point -3, because now it passes when y = 0.
So, as we want that function remains the same and only the interception on the Y-axis to be different, the correct alternative is the letter D. g(x) = (- x)² – 3.
Look at the graph of g(x) = (- x)² – 3 below: