Which statement best expresses the central idea of the text?
A.
People act kindly when they do good without receiving anything in return.
B.
Most people's acts of kindness are selfish because they expect something in
return.
C.
The brain rewards acts of kindness because positive social connections are
necessary for survival.
D.
Showing kindness toward others can improve one's mood and strengthen one's
identity as a good person.