By a comparison between past problems and present ones the author draws attention to the ______.

A．find a way of solving the Denny Doodlebug problem
B．realize how little we know about the complexity of human behavior
C．bring to light codes of some societies which we didn't know before
D．be aware of the difficulties of communications between different cultures

A．people in the same society may be governed by different cultural codes
B．the influence of cultural codes on an individual may decrease as he becomes older
C．cultural codes are passed on from one generation to another either in written form or in oral form or in both
D．cultural codes in different cultures may differ sharply from one another