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