Consider the following statements regarding streamline(s):
(i) It is a continuous line such that the tangent at any point on it shows the velocity vector at the point.
(ii) There is no flow across streamlines
(iii) $\frac{dx}{u}=\frac{dy}{v}=\frac{dz}{w}$ 
is the differential equation of a streamline, where u, v and w are velocities in directions x, y and z, respectively
(iv) In an unsteady flow, the path of a particle is a streamline
Which one of the following combinations of the statements is true?
(a) (i), (ii), (iv) (b) (ii), (iii), (iv)
(c) (i), (iii), (iv) (d) (i), (ii), (iii)