4. Answer the questions about the function shown in the accompanying contour map and gradient vector plot, assuming the standard direction for the domain coordinate axes: a. What are the signs of the partial derivatives at A? (4) b. What is the sign of the directional derivative at B in the direction of the vector W (it's marked on the map)? (4) c. Mark on the map the locations of the local maxima and saddle points. (4) B