Answer:
b)
Explanation:
The 3 frequencies found in the sound waveform (400, 1600, and 2400 Hz are related between them, being 400 Hz the fundamental frequency of the sound, and 1600 Hz and 2400 Hz, harmonics (overtones of the fundamental) according to this relationship:
1600 Hz = 4* 400 Hz (4th Harmonic)
2400 Hz = 6* 400 Hz (6th Harmonic)