How doe your parasympathetic nervous system use feedback to keep you healthy? a. it triggers a fight-or-flight response when danger has passed.
b. it dilates your pupils when you are in bright light.
c. it lowers your heart rate after danger has passed
d. it calms you down when you are in danger.

d. it calms you down when you are in danger.

Explanation:

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

the correct answer is b