We can learn from the passage that ______.
A．higher-degree-holders are surely going to make more money
B．college graduates in different majors usually get paid differently
C．a master's degree-holder in social work will surely make more money than a bachelor' s degree-holder in computer science
D．if one wants to earn $ 4.4 million, he or she has to try to get a professional degree such as a doctor or lawyer