Final answer:
Trait theories explain differences in thrill-seeking behavior by variations in ideal levels of internal arousal.
Step-by-step explanation:
Trait theories of personality suggest that differences in thrill-seeking behavior can be explained by variations in ideal levels of internal arousal. According to these theories, individuals have different ideal levels of internal arousal, which can influence their tendency to engage in thrill-seeking behaviors.
Based on this information, we can determine that Nathan and Ellie may have different ideal levels of internal arousal. It is incorrect to assume that they have the same ideal level of internal arousal or that they have no ideal level of internal arousal. Without further information about Nathan and Ellie's specific personality traits or behaviors, we cannot determine which one of them has a higher ideal level of internal arousal.