Question 15 (6 points) Describe the level curves for the function f(x, y) = x2 + y2 for the c-values given by c = 0, 2. O a) c = 0; 8=22+32 c = 2; 6 =x2+32 O b) c = 0; 0 = 22 + 32 c =2; 2=*+ 32 O c) c = 0; 2 = *+ c = 2; 4 = +y O d) c= 0; 4= 22 + 32 c =2;6 =*+ 32