Final answer:
The sympathetic nervous system increases physiological arousal in response to stress, while the parasympathetic nervous system promotes a calm state, focusing on 'rest and digest' activities.
Step-by-step explanation:
One major difference between the sympathetic and parasympathetic nervous systems is their roles in the body's response to certain situations. (A) states correctly that the sympathetic nervous system increases physiological arousal, preparing the body for 'fight-or-flight' during stressful scenarios. In contrast, the parasympathetic nervous system calms the body down after such arousal, returning it to a 'rest and digest' state. Neither system is a subdivision of the somatic nervous system as suggested in (B), both are parts of the autonomic nervous system.
While the sympathetic nervous system does play a role during traumatic events, it is not its sole function, making (C) incorrect. The parasympathetic nervous system is also not solely concerned with digestion. It is inaccurate to say that one system is used more often than the other, as suggested in (D), because they are both active at different times to maintain homeostasis. Lastly, (E) is incorrect as both systems play roles in sexual behavior, among other functions. The correct answer is (A), emphasizing the opposing but complementary roles of these two divisions of the autonomic nervous system.