"The Fight or Flight Response Is a Physiological Reaction Triggered

"The Fight or Flight response is a physiological reaction triggered by fearful events. Fear is a normal emotion felt in response to a threat or imminent danger. The autonomic nervous system is the main mechanism in control of this response and its role is mediated by the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system activates the physiological changes that occur during the Fight or Flight response, releasing norepinephrine. The parasympathetic nervous system acts together with the sympathetic system, returning the body to homeostasis with the release of the neurotransmitter acetylcholine." This is an example of:

A) developmental explanation
B) mechanistic explanation
C) cultural explanation
D) adaptive explanation