The Fact That Some People Will Work Hard to Earn

The fact that some people will work hard to earn a lot of money while others will be content with much less income indicates that

A) worker preferences are an important source of earning differentials.
B) economics ranks one set of worker preferences as more desirable than another.
C) some people can be paid less for doing hard work while others have to be paid a premium for doing a similar task.
D) skill levels of laborers are a minor consideration in wage rate determination.