They all produce light. They all cause vibrations. They all convert heat to energy. They all need gravity to move.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: What do playing a guitar, banging a drum, and dropping a pebble in the water have in common?
Possibilities:
- They all produce light.
- They all cause vibrations.
- They all convert heat to energy.
- They all need gravity to move.

They all cause vibrations.