The function f(x, y) = xy sin(1/x)
when (x =| 0), and f(0, y) = 0
(A) has both partial derivatives at (0; 1). (B) is dierentiable at (0; 0) and discontinuous at (1; 0).
(C) is continuous at (1; 0) and dierentiable (D) is continuous at (0; 0) and dierentiable at (1; 0).
everywhere in R2. (E) none of the above.