A metre scale is moving with uniform velocity. This implies

The correct option is: the force acting on the scale is zero and the torque acting about centre of mass of the scale is also zero.

Let us analyze the physical conditions implied by the motion of the metre scale:
1. The problem states that the metre scale is moving with a uniform velocity. Uniform velocity means that both the speed and the direction of motion of the scale are constant over time. Therefore, the acceleration of the scale (both linear and angular) is zero.

2. According to Newton's second law of motion, the net external force acting on a body is directly proportional to its linear acceleration:
$F=ma$
Since the metre scale is moving with a constant velocity, its linear acceleration is zero ($a=0$). This directly implies that the net external force acting on the scale must be zero:
$F_{\text{net}}=0$

3. Furthermore, because the scale is moving with a uniform velocity without any rotation or change in orientation, its angular acceleration ($\alpha$) about any point, including its centre of mass, is also zero ($\alpha =0$).
The net torque acting on a rigid body is related to its angular acceleration about its centre of mass by:
$\tau =I\alpha$
Since the angular acceleration is zero, the net torque acting about the centre of mass must also be zero:
${\tau }_{\text{net}}=0$

Therefore, for a body moving with a uniform velocity, both the net external force acting on it and the net torque acting about its centre of mass must be zero.