Final answer:
When Julia thought she saw a shark, her sympathetic nervous system was activated. Upon realizing it was just a bottle, her parasympathetic nervous system took over to calm her down. The answer is A) Sympathetic; Parasympathetic.
Step-by-step explanation:
When Julia thought she saw a shark while swimming, her sympathetic nervous system would have been activated. This division of the autonomic nervous system prepares the body for stressful situations by initiating a "fight or flight" response, which could include an increased heart rate and a rush of adrenaline.
Once she realized that it was just a floating bottle and was no longer under stress, her parasympathetic nervous system would be activated to calm her body down and return to a state of rest, also known as the "rest and digest" response. Therefore, the correct answer to the question is A) Sympathetic; Parasympathetic.