What influence does the current research on kindness have on our understanding of what makes us happy? A) Researchers now know that smiles are catching: if someone smiles it makes us want to smile too.

B) Research shows that people are motivated by reciprocity (the returning of a favor), which lifts people's moods.

C) Research shows that the 'feel-good' section of the brain, the striatum, is activated when we show kindness to others, as it responds to things we find rewarding.

D) The research shows what we already know about kindness and there will be no need for future research.