By saying "Indeed, many of the things we think of as ’100 percent American’ came from other cultures" (Line 3, Para.1), the author suggests that the American culture is ______.

A．Judging people’s behavior.
B．Changing people’s attitudes.
C．Common causes of anger.
D．The effects of negative behavior.

A．Three kinds of motivation and its different effectiveness.
B．Negative outcomes of three kinds of motivation.
C．The combination of three forms of motivation.
D．How to make full use of three forms of motivation.