Find fx(x,y) and fy(x,y), and explain why f(x,y) has no local extrema. f(x,y) =4.4 -2.1x +7.2y +0.4y +x2 A . . . fx ( x, y) = fy (x,y) = Choose the best explanation below for the reason that f(x,y) has no local extrema. O A. The functions fx(x,y) and fy(x,y) are never equal to each other. O B. The function fy(x,y) is always positive while the function f(x,y) is always negative. O C. The function fy(x,y) can never equal zero. O D. The function fx(x,y) can never equal zero