Which is not a fight or flight reaction
a. digestive system shuts down
b. metabolism speeds down
c. blood glucose increases
d. muscles tense?

Digestive  system shuts down is not  a fight or flight reaction.

B

Explanation:

The fight-or-flight response, also known as the acute stress response, refers to a physiological reaction that occurs in the presence of something that is terrifying, either mentally or physically.

IMMEDIATE PHYSIOLOGICAL REACTIONS INCLUDE:

Acceleration of heart and lung action Paling or flushing, or alternating between both Inhibition of stomach and upper-intestinal action to the point where digestion slows down or stops General effect on the sphincters of the body Constriction of blood vessels in many parts of the body Liberation of metabolic energy sources (particularly fat and glycogen) for muscular action Dilation of blood vessels for muscles Inhibition of the lacrimal gland (responsible for tear production) and salivation Dilation of pupil (mydriasis) Relaxation of bladder Inhibition of erection Loss of hearing Tunnel vision (loss of peripheral vision) Disinhibition of spinal reflexes TremorsIncreased muscle tension in order to provide the body with extra speed and strength.

Covalent bond is the correct answer