Which of the following symptoms is commonly associated with anxiety disorders?

Rapid heart rate is commonly associated with anxiety disorders as it is a physical symptom that occurs in response to stress or fear. When a person experiences anxiety, their body activates the "fight or flight" response, leading to various physiological changes. One of these changes is an increase in heart rate, also known as tachycardia. This reaction is part of the body's natural response to prepare for perceived threats, making it a hallmark symptom of anxiety disorders.

In contrast, increased energy is often associated with hyperactivity or excitement rather than anxiety. Excessive sleeping may indicate depression or exhaustion, which are not typical symptoms of anxiety disorders but rather related conditions. Aversion to social activities can be linked to social anxiety disorder, but it does not specifically capture the physiological response of anxiety like a rapid heart rate does. Therefore, the presence of a rapid heart rate is a direct indicator of the body’s response to anxiety, making it the most suitable choice in this context.