The speech of the mechanic addressed to the retired brigadier's wife is an example of ______.

A．Nowadays, English schoolboys are impolite toward people except towards their teachers.
B．The way of asking time is different from that of earlier generations.
C．People's speaking styles vary according to different situations.
D．People's ways of speaking are relatively stable on varying occasions.

A．The reporters asked some difficult and embarrassing questions.
B．President Kennedy unconsciously sought social integration with other people.
C．President Kennedy was imitating the reporters.
D．President Kennedy preferred talking equilibrium in his conversation.