Which of the following best describes the author's tone in the passage

A．teachers are the moral models of young children
B．teachers at elementary level of schools are of great help to the children's career success
C．one's early education influences him all his life
D．children are more purer at their early age and early school years are their best memory

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．more education in primary school or still earlier should be much emphasized