Answer: The correct answer is " longitudinal wave with air molecules
vibrating parallel to the direction of travel".
Step-by-step explanation:
In longitudinal wave, the particles vibrate parallel to the direction to the propagation of the wave. For example, sound wave is a longitudinal wave.
It needs a medium for its propagation. It can travel in solid, liquid and gas. It travel faster in solid in comparison to the liquid.
In the given problem, a tuning fork vibrates at a frequency of 512 hertz when struck with a rubber hammer. The sound produced by the tuning fork will travel through air. Here, a longitudinal wave with air molecules vibrating parallel to the direction of travel.
Therefore, the correct option is (1).