Final answer:
The rate of voltage oscillation in a synchrotron increases as the particle completes each loop.
Step-by-step explanation:
The rate of voltage oscillation increases as the particle travels faster and faster on each loop in a synchrotron.
In a synchrotron, the frequency of the accelerating voltages is increased as the particle travels faster, causing the beam particles to travel the same distance in a shorter time. This increase in frequency results in an increase in the rate of voltage oscillation.
Therefore, the correct answer is a) Increases.