According to the passage, the author considers the reduction of energy in an empty region of space to which a real particle has been added to be ______.

A．Chimpanzees' sense of time is as good as man's.
B．Man developed from apes.
C．Memory and foresight contribute to intelligence.
D．Monkeys and apes are almost as intelligent as man.

A．uncertainties
B．dependent conditions
C．incidental thoughts
D．events that may occur