**Core Concept**
Generalized anxiety disorder (GAD) is a psychiatric condition characterized by excessive and persistent worry about various aspects of life, which is not limited to a specific situation or object. This worry is often accompanied by physical symptoms such as restlessness, fatigue, difficulty concentrating, irritability, muscle tension, and sleep disturbances.

**Why the Correct Answer is Right**
The correct answer, "Anxiety about specific situations," is incorrect. GAD is distinguished from other anxiety disorders by its pervasive and diffuse nature, where individuals experience worry about multiple areas of life, such as work, finances, relationships, and health, without a specific trigger or focus. This excessive worry is often accompanied by physical symptoms, which can be debilitating and interfere with daily functioning. In contrast, specific phobias or situational anxiety disorders are characterized by a more focused fear or anxiety response to a specific object or situation.

**Why Each Wrong Option is Incorrect**
**Option A:** "Free floating anxiety" is a characteristic of anxiety neurosis, which is now considered an outdated term. Free floating anxiety refers to a diffuse sense of anxiety without a specific focus, but it is not a specific diagnostic criterion for GAD.

**Option B:** "Worry about trivial issues" is not a defining feature of GAD. While individuals with GAD may worry about trivial issues, this is not a distinguishing characteristic of the disorder. In fact, the worry in GAD is often focused on significant life issues, such as finances, relationships, or health.

**Option C:** "Inability to relax" is a common symptom of GAD, but it is not a defining characteristic of the disorder. Many individuals with GAD experience physical symptoms such as restlessness, fatigue, and muscle tension, which can make it difficult to relax. However, the inability to relax is not a specific diagnostic criterion for GAD.

**Clinical Pearl / High-Yield Fact**
It's essential to note that GAD often co-occurs with other psychiatric conditions, such as depression, substance use disorders, or other anxiety disorders. A comprehensive diagnostic evaluation is necessary to determine the presence of comorbid conditions.

**✓ Correct Answer:** D. Anxiety about specific situations