A one dimensional flow is one which is

Why One Dimensional Flow Uniform?

Uniform flow

When the velocity and other hydrodynamic parameters in the flow field remain constant from one place to the next at any given instant of time, the flow is said to be uniform. There won't be any spatial distribution of hydrodynamic and other factors for a uniform flow.

irregular flow

Non-uniform flow is described as when the velocity and other hydrodynamic parameters vary from one location to another.

constant flow

A steady flow is characterised as one in which the various fluid characteristics and hydrodynamic parameters at any site remain constant across time.

One-dimensional flow

This flow allows all flow parameters to be represented as functions of only one space coordinate and one time unit. The distance along the fluid's flow centerline, which need not be straight, is often the single space coordinate. For instance, when differences in pressure and velocity occur along the length of a pipe, the flow is thought to be one-dimensional; however, any fluctuation over the cross-section is seen to be insignificant.

Turbulent fluid motion

It can be viewed as an irregular flow condition where different parameters (such pressure and velocity components) exhibit a random change with time and space.

Summary:

A one dimensional flow is one which? (a) Is uniform (b) Is steady uniform (c) Takes place in straight lines (d) Involves zero transverse components of flow

The one which is uniform is the one-dimensional flow. There is no components of flow in one-dimensional flow. It is called uniform when velocity and other hydrodynamic parameters do not change with respect to time.