ANS:C - both (a) & (b)

In the case of streamline flow, the velocity at a certain point satisfies the following conditions:

• Constant: The velocity at any point within a streamline (a path followed by a fluid particle) remains constant as long as the flow conditions (such as fluid properties and external forces) do not change.
• Independent of Time: Streamline flow implies that each fluid particle follows a path where its velocity vector at any instant is tangent to the streamline at that point. This implies that the velocity at a certain point in streamline flow is independent of time, meaning it remains constant along the streamline.

• The velocity at a certain point is constant.
• The velocity at a certain point is independent of time.