According to the author, some politicians attribute the society's deteriorated moral values to ______.

A．it's easy to carry moral education at and above high school level
B．high school students don't need any further moral education
C．no return is to be gained on the investment in moral education
D．moral education in primary school or still earlier should be much emphasized

A．the past ways for ruling a society
B．the society's established virtues
C．the out-of-date moral conducts
D．the previous legal systems