When was the jigsaw puzzle first invented

A．to make known his point of view in the debate on bilingualism
B．to arouse peoples' sympathy for the minorities
C．to advocate educational reforms
D．to present facts concerning bilingualism

A．are being phased out in the U.S.
B．are rejected by minorities
C．are approved by the majority of San Fransico's voters
D．are backed up by the government and legislature