The proposal to lay a telegraph cable from Europe to America made oceanographic studies take on a(n) ______.

A．how Cultural Survival, Inc. helped a tribe to solve the problem of copper mining
B．why local cultures should be saved
C．the work of Cultural Survival, Inc
D．the difficulties in saving local cultures

A．learn something while keeping something of its own
B．remain what they used to be
C．change itself as more, as it can
D．be careful in order not to be cheated