【单选题】

The "so-called fight-or-flight response" (Line 2, Para.1) refers to " ______ ".
A．the biological process in which human beings' sense of self-defense evolves

B．the instinctive fear human beings feel when faced with potential danger
C．the act of evaluating a dangerous situation and making a quick decision
D．the elaborate mechanism in the human brain for retrieving information