Streamline flow:
Streamline flow refers to the flow of a fluid in which all particles move in parallel paths, with no mixing or crossing of the paths. In this type of flow, the fluid particles move smoothly, without any turbulence or eddies.

Laminar flow:
Laminar flow is a type of streamline flow in which fluid particles move in parallel layers or laminae. Each layer slides smoothly over the adjacent layers, with no mixing or crossing of the layers. In laminar flow, the fluid motion is characterized by smooth and continuous streamlines.

Viscous flow:
Viscous flow is a type of flow in which the fluid particles experience internal friction or viscosity. Viscosity is the property of a fluid that determines its resistance to shear or flow. In viscous flow, the fluid particles slide past each other with some resistance, resulting in internal friction.

All of the mentioned:
The correct answer to the given question is option 'D' - All of the mentioned. This is because when all particles of a fluid have a path parallel to a wall, it indicates both streamline flow and laminar flow. Streamline flow implies that the fluid particles move smoothly in parallel paths, while laminar flow indicates that the fluid particles move in parallel layers or laminae. Additionally, since the fluid particles experience internal friction or viscosity in this scenario, it can also be considered as a type of viscous flow.

Therefore, when all particles of a fluid have a path parallel to a wall, it exhibits streamline flow, laminar flow, and viscous flow simultaneously, which is represented by the option 'D' - All of the mentioned.