The correct answer is: A. Reduced velocity lag error.
Friction is a force that opposes the relative motion of two surfaces in contact. In a system, friction can cause a delay in the response of the system to a change in input. This is because the friction force must be overcome before the system can move.
A low friction coefficient means that there is less friction between the surfaces in contact. This means that the system will be able to respond more quickly to a change in input. As a result, the velocity lag error will be reduced.
The other options are incorrect because they are not directly related to the friction coefficient. Option B, increased velocity lag error, is the opposite of what would be expected with a low friction coefficient. Option C, increased speed of response, is not necessarily true, as the speed of response depends on other factors besides the friction coefficient. Option D, reduced time constant of the system, is also not necessarily true, as the time constant of the system depends on the inertia of the system and the damping coefficient, as well as the friction coefficient.