The author in the passage uses the following devices in his writing EXCEPT______.

A．Evolution of speech
B．Darwin's law of natural selection
C．Progress of human brains
D．Evolution of human intelligence

A．Corporations attempt to cash in on the crisis in education.
B．Communications broadcasts into almost 12,000 junior high and high schools.
C．Education no longer becomes a learning process.
D．This article illustrates free markets and free minds are mutually exclusive.