Which disorder is characterized by chronic physiological arousal and avoidance of trauma-related stimuli?

Posttraumatic Stress Disorder (PTSD) is specifically characterized by chronic physiological arousal and avoidance behaviors following exposure to a traumatic event. Individuals with PTSD often experience heightened levels of anxiety, intrusive thoughts, and emotional numbness related to the trauma. They may avoid reminders of the trauma, including places, people, or conversations that trigger distressing memories. This set of symptoms can persist for an extended period, making it distinct from other anxiety-related disorders.

In contrast, Generalized Anxiety Disorder involves excessive worry across various situations but does not necessarily include trauma-specific symptoms. Obsessive-Compulsive Disorder focuses on the presence of intrusive thoughts and compulsive behaviors, which do not directly relate to trauma experiences. An Acute Stress Reaction occurs in the immediate aftermath of a traumatic event, typically lasting from a few days up to a month, and while it may include similar symptoms, it does not meet the criteria for chronicity that defines PTSD. Thus, PTSD is the most accurate answer when considering the specific features mentioned in the question.