velocity component of potential flow

Question

The velocity components in the x and y directions of a two dimensional potential flow are u and v, respectively. Then $\frac{\partial u}{\rho y}$ is equal to                                          

      (a) $\frac{\partial v}{\rho x}$                                                                  (b)$-\frac{\partial v}{\rho x}$  

      (c) $\frac{\partial v}{\rho y}$                                                                  (d) $-\frac{\partial v}{\rho y}$