Find the Domain and Range and Describe the Level Curves $$f ( x , y ) = \frac { 9 x ^ { 2 } } { y }$$

Multiple Choice

Find the domain and range and describe the level curves for the function f(x,y) .
- $$f ( x , y ) = \frac { 9 x ^ { 2 } } { y }$$

A) Domain: all points in the $x y$ -plane; range: real numbers $z \geq 0$ ; level curves: parabolas $y = x ^ { 2 }$
B) Domain: all points in the $x y$ -plane except $y = 0$ ; range: real numbers $z \geq 0$ ; level curves: parabolas $y = c x ^ { 2 }$
C) Domain: all points in the $x y$ -plane; range: all real numbers; level curves: parabolas $y = c x ^ { 2 }$
D) Domain: all points in the $x y$ -plane except $y = 0$ ; range: all real numbers; level curves: parabolas $y = x ^ { 2 }$