Answer:
The correct answer is the number 4. A wave on a pond is a mechanical wave which requires a medium to travel.
Explanation:
Mechanical waves are those that need a material medium to propagate. The waves of the sea and the waves that we produce on a guitar string, the sound, are examples of mechanical waves. Electromagnetic waves are energetic pulses capable of propagating in a vacuum. This way, a wave on a pond is a mechanical wave which requires a medium to travel.