If f(x,y)=cos(x)sin(y)f(x,y) = \cos(x) \sin(y)f(x,y)=cos(x)sin(y), which of the following is the second partial derivative fyyf_{yy}fyy?
−cos(x)sin(y)-\cos(x) \sin(y)−cos(x)sin(y)
−sin(x)cos(y)-\sin(x) \cos(y)−sin(x)cos(y)
cos(x)cos(y)\cos(x) \cos(y)cos(x)cos(y)
−cos(x)cos(y)-\cos(x) \cos(y)−cos(x)cos(y)