Find f, (x y) and f (x,y), and explain why f(x,y) has no local extrema. fix.y) = 3.7 - 1.4x + 7.6y + 0.3y"+x 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 function f (x,y) can never equal zero. O B. The functions f, (x,y) and f (x,y) are never equal to each other. O C. The function f (x,y) can never equal zero. O D. The function f (x,y) is always positive while the function f, (x,y) is always negative