When a tuning fork vibrates over an open pipe and the air in the pipe starts to vibrate, the vibrations in the tube are caused by
a. harmonics.
b. beats.
c. reinforcement.
d. resonance.

The correct answer would be d. resonance

Resonance is the phenomenon which occurs when the frequency of the forced vibrations is almost equal to the natural frequency of the system. It amplifies the sound produced by the system.

Similarly, when the tuning fork is vibrated at the natural frequency of the open pipe, the air in the pipe starts vibrating at the same frequency and results in the increased amplitude of the sound.

yes it is   dangerous

explanation:

because that foot is discusting and could get you sick