Question 12 (0.01 points) Consider the surface defined by 2 = /(, y) = > + y + 1. (a) Draw and clearly label the contours for the heightsz = 0, z = 1, and z = 2. (b) Evaluate the gradient of f (T, y ) at the point (X, ?) = (0, -1), and draw the gradient vector on the contour diagram. (c) Compute the directional derivative at (or, y ) = (0, -1 ) in the direction (2, 1). (d) Without calculation, identify the ( D, ? ) point where the global minimum of the function occurs on the domain shown, -2 _ _ 2 and - 2 - y -2. Explain your answer briefly