In the author’s opinion, technical progress such as inventions of gunpowder and the mariner’s compass during the civilized process cannot be ______ to the power of speech, writing and agriculture.

A．To show the relationship between fearfulness and environment.
B．To give examples of animals that aren’t fearful.
C．To compare fear in mammals to fear in other animals.
D．To identify the nerves that control fear in certain animals.