How can doing something for someone else relieve stress

How can doing something for someone else help relieve stress:

Give advice good qualities.
- Make walking every day
- Exercise regularly, learn effective relaxation techniques to reduce stress and sleep longer
- breathe deeply
- listen to music
- Breathe essential oils of lavender
- Practice of yoga, meditation
- Train yourself to do progressive muscle relaxation

Ithink the answer is b hope this

1. the answer is a parasite