Find an Expression for the Function $y=f(x)$ Whose Graph Is the Bottom Half of the Parabola

Multiple Choice

Find an expression for the function $y=f(x)$ whose graph is the bottom half of the parabola $x+(6-y) ^{2}=0$ .

A) $y=6-\sqrt{-x}$
B) $y=36-\sqrt{-x}$
C) $y=6+\sqrt{x}$
D) $y=36-x^{2}$
E) $y=6-x^{2}$