The information given by the lie detector, according to the author, is ______.

A．direct experiences are more valuable than indirect ones
B．whatever attitudes a child learns in school have already been introduced at home
C．teachers can sometimes have an unwholesome influence, on children
D．most children fear policemen

A．physiological changes will for sure betray a liar
B．the bigger a lie is, the stronger the strain will be
C．the degree of the strain depends on the purpose of lying
D．a well-trained person can tell lies without being detected