A method of communication not mentioned or intimated by the author is the ______.

A．home training is more important than school training because a child spends too many hours with his parents
B．teachers can and should help parents to understand further the objectives of the school
C．there are many ways in which the mathematics program can be implemented at home
D．parents have a responsibility to help students in doing homework

A．father's helping his son with the latter's studies.
B．written communications to the latter's studies.
C．having the parent observe lessons which the children are being taught
D．principal-parent conferences rather than teacher-parent conferences.