A contour diagram for the smooth function z=f(x,y) is shown below.(a) Is z an increasing or decreasing function of x?Of y?(b) Is fx positive or negative?How about fy?(c) Is f positive or negative?How about fyy?(d) In what direction does gradf point at point P?in the direction (Give a vector that points generally in the right Evirection.)In what direction does gradf point at point Q?in the direction (Again, give a vector that points generally in the right direction.)(e) Is gradf longer at P or at Q?lote: You can earn partial credit on this problem.