Which of these excerpts is one of the main arguments in jack london's "the human drift"?

a. the history of civilization is a history of wandering, sword in hand, in search of food.
b. as soon as [man's] evolution permitted, he made himself better devices for killing than the old natural ones of fang and claw.
c. and yet, despite this terrible roll of death, there are to-day alive on the planet a billion and three quarters of human beings.
d. and to this day, [man's] finest creative energy and technical skill are devoted to the same old task of making better and ever better killing weapons.