The smile on American's face is usually linked to happiness. The smile by a Japanese is habitual and polite expression. Even when angry or sad, they will probably show a smile on the face. This shows:
选项：

A:The emotional culture and neutral culture will affect people's facial expressions.;
B:The United States is an emotional culture, while Japan is a neutral culture.;
C:For a neutral culture, the expressed emotion is sometimes inconsistent with the real emotion.;
D:When people from different cultures meet, they may misunderstand facial expressions.