Hefei chunzhao

From the topic, it takes 0.2s for the vibrator to go from A to B. When the vibrator passes through A and B, the speed is the same, so A and B are symmetrical about the equilibrium position. The shortest time for the vibrator to return from B to A is 0.4s, and the time for the vibrator to go from B to C and then to B is 0.2s. According to symmetry analysis, the total time for the vibrator to go from A to B to C to D to A is T=0.8s, that is, the vibration period of the vibrator is T=

So choose B.