ANS:C - stagnation point

The point where no motion occurs in a flow field is known as a stagnation point. In fluid dynamics, at a stagnation point, the velocity of the fluid is zero. In the given velocity components u=ax and v=by, a stagnation point occurs when both u and v are zero. In other words, a stagnation point is where the velocity vector field goes to zero. Hence, the correct term for the point where no motion occurs in this context is a stagnation point.