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: real numbers z ≤ 0; level curves: lines 8x - 10y = c, c ≤ 0

B) Domain: all points in the xy-plane; range: real numbers z ≥ 0; level curves: lines 8x - 10y = c

C) Domain: all points in the xy-plane; range: all real numbers; level curves: lines 8x - 10y = c, c ≥ 0

D) Domain: all points in the xy-plane; range: all real numbers; level curves: lines 8x - 10y = c