If f(x,y)=ln(x)ln(y)f(x, y) = \ln(x) \ln(y)f(x,y)=ln(x)ln(y) is defined for x>0x > 0x>0 and y>0y > 0y>0, what is the partial derivative ∂f∂x\frac{\partial f}{\partial x}∂x∂f?
ln(y)x\frac{\ln(y)}{x}xln(y)
ln(x)y\frac{\ln(x)}{y}yln(x)
1xy\frac{1}{xy}xy1
1x+1y\frac{1}{x} + \frac{1}{y}x1+y1