Find the first partial derivatives of $f(x,y,z) = z \ \arctan(\frac{y}{x})$ at the point (4, 4, -3).

A. $\frac{\partial f}{\partial x}(4, 4, -3) =$

B. $\frac{\partial f}{\partial y}(4, 4, -3) =$

C. $\frac{\partial f}{\partial z}(4, 4, -3) =$