Two magnets `A` and `B` are identical in mass, length and breadth but have different magnetic moments. In a vibration magnetometer, if the time period of `B` is twice the time period of `A`. The ratio of the magnetic moment `M_(A)//M_(B)` of the magnets will be
A. `1//2`
B. 2
C. 4
D. `1//4`
