The other passengers on the bus were quite loud, so he put on his headphones to relax and what?\nOptions:\n- go to bed\n- sleep\n- listen to music\n- stretch out\n- stop worrying
A step-by-step solution is:
listen to music
After listening music, a person feels relaxed.

As the other passengers on the bus were quite loud so he put on his headphones to relax and listen to the music.

.

The final answer: listen to music