John has a severe snake phobia. he experiences a flight or fight response when he sees one. this reaction is caused by the nervous system.

The correct answer is the sympathetic nervous system.  

The autonomic nervous system works to monitor the unconscious activities of the body. The sympathetic nervous system main procedure is to instigate the fight or flight response of the body. However, it is spontaneously active at a fundamental level to sustain homeostasis homeodynamics.  

In reaction to a stressor, the sympathetic nervous system orchestrates what one generally knew as the flight or fight response. It enhances the tension and flow of blood in the muscle, accelerates the rate of heart and respiration, dilates the pupil, and enhances arterial blood pressure and perspiration.  

image result for describe the various types of gene mutationsghr.nlm.nih.gov

the types of mutations include: missense mutation: this type of mutation is a change in one dna base pair that results in the substitution of one amino acid for another in the protein made by a gene. nonsense mutation: a nonsense mutation is also a change in one dna base pair.

explanation:

meiosis is the correct answer