Find the Domain and Range and Describe the Level Curves

Multiple Choice

Find the domain and range and describe the level curves for the function f(x,y) .
-f(x, y) = ( + )

A) Domain: all points in the xy-plane; range: all real numbers; level curves: circles with centers at (0, 0)

B) Domain: all points in the xy-plane satisfying x² + y² ≤ 1; range: real numbers ≤ z ≤ ; level curves: circles with centers at (0, 0)

C) Domain: all points in the xy-plane satisfying x² + y² ≤ 1; range: real numbers - 11efabfd_aa12_34a1_af07_d19efc43c81a_TB9662_00 ≤ z ≤11efabfd_aa12_34a1_af07_d19efc43c81a_TB9662_00 ; level curves: circles with centers at (0,0) and radii r, 0 < r ≤ 1

D) Domain: all points in the xy-plane; range: real numbers - 11efabfd_aa12_34a1_af07_d19efc43c81a_TB9662_00 ≤ z ≤ 11efabfd_aa12_34a1_af07_d19efc43c81a_TB9662_00 ; level curves: circles with centers at (0, 0)