The correct answer is: A. improve its ventilation.
The two holes in the disc of energy meter are drilled at the opposite sides of the spindle to improve its ventilation. This is because the holes allow air to flow through the disc, which helps to keep it cool. If the disc were not ventilated, it would overheat and could cause the meter to malfunction.
Option B is incorrect because the holes do not eliminate creeping at no load. Creeping is a phenomenon that occurs when a meter continues to rotate even when there is no load on it. This can be caused by a number of factors, including friction between the disc and the spindle, and the elasticity of the disc. The holes in the disc do not affect these factors, so they do not eliminate creeping at no load.
Option C is incorrect because the holes do not increase the deflecting torque. The deflecting torque is the torque that causes the disc to rotate. It is created by the magnetic field of the meter’s coil. The holes in the disc do not affect the magnetic field, so they do not increase the deflecting torque.
Option D is incorrect because the holes do not increase the braking torque. The braking torque is the torque that opposes the rotation of the disc. It is created by the friction between the disc and the spindle. The holes in the disc do not affect the friction, so they do not increase the braking torque.