Final answer:
The sympathetic nervous system was in control of Jonathan's response to the snake, triggering the fight-or-flight response, which includes an accelerated heart rate and increased energy. Once the threat was gone, the parasympathetic nervous system helped Jonathan calm down.
Step-by-step explanation:
The system primarily in control of Jonathan's response when a snake crossed his path is the sympathetic nervous system. This response is part of the autonomic nervous system and is specifically responsible for the fight-or-flight reaction that an animal or human exhibits when encountering a potentially dangerous situation. The immediate reactions such as an accelerated heart rate and increased energy, followed by a return to calmness once the threat has passed (mediated by the parasympathetic nervous system), demonstrate the balance the autonomic nervous system maintains through its sympathetic and parasympathetic divisions.
Certain hormones, such as adrenaline, are released during the fight-or-flight response, but they are not the primary systems controlling the response; instead, they assist the nervous system in preparing the body for action. Therefore, the correct answer to Jonathan's response to seeing a snake is b) Sympathetic nervous system.