Describe the Level Curves of the Function F(x,y) =

Multiple Choice

Describe the level curves of the function f(x,y) = , where a > 0.

A) all circles in the xy-plane
B) all circles in the xy-plane having centres at the origin.
C) all circles in the xy-plane having centres at the origin and radii less than a
D) the origin together with all circles in the xy-plane having centres at the origin and radii in the interval (0, a]
E) a circle in the xy -plane having its centre at the origin and radius = a