题目内容：
请根据短文内容，回答题。The American definition of success is largely one of acquiring wealth and a high material standard of living．It is not surprising，____51____，that kmericans have valued education for its monetary value．The belief is widespread in the United States____52____the more schooling people have，the more money they will make when they leave sch001．The belief is strongly reflecting the desirability of an undergraduate university degree，or a professional degree such as medicine or law ____53____ the undergraduate degree．The money value of graduate degrees in ____54____ such as art，history，or philosophy is not yet great．
This belief in the monetary value of education is ____55____ by research outcomes on income．Ben Wattenberg，a social scientist，estimates that in the ____56____ of a lifetime a man with a college school diploma in l972 could earn about$380，000 more than a man who only had a high school diploma．
Perhaps this helps to explain survey ____57____ which showed that Americans who wished they had lived their lives differently in some way regretted ____58____ of all that they did not get more education．The regret is ____59____ by those who have made themselves to the top and by those who have not．Even a man like Douglas Fraser，the president of the United Auto Workers Union，a nationally known and successful leader，was troubled by regrets that he did not climb higher on the ____60____ ladder．
_________ A．however
B．therefore
C．moreover
D．though
