The frequencies of the primary magnetic field generated by worldwide thunderstorm

Q. The frequencies of the primary magnetic field generated by worldwide thunderstorm activity vary in the range

(A) 10^-6 Hz -10^-3 Hz                                             (B) 10^-3 Hz -1 Hz

(C) 1 Hz -10³ Hz                                           (D) 10³ Hz -10⁶ Hz

Ans: 1 Hz -10³ Hz