**Core Concept**
Bulimia nervosa is a complex eating disorder characterized by recurring episodes of binge eating followed by compensatory behaviors, often involving purging or excessive exercise. The diagnosis of bulimia nervosa is based on specific duration criteria, which is essential for distinguishing it from other eating disorders.

**Why the Correct Answer is Right**
According to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5), the duration criteria for bulimia nervosa is a minimum of 3 months. This duration ensures that the individual has experienced a persistent pattern of disordered eating behavior, making it a severe and chronic condition. The DSM-5 emphasizes that this duration criterion is crucial for differentiating bulimia nervosa from other eating disorders, such as binge eating disorder.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because there is no duration criteria specified for bulimia nervosa in the DSM-5.
* **Option B:** This option is incorrect because the DSM-5 does not specify a duration of 6 months for bulimia nervosa.
* **Option C:** This option is incorrect because the DSM-5 does not specify a duration of 1 year for bulimia nervosa.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the duration criteria for bulimia nervosa can vary depending on the diagnostic criteria used. However, the DSM-5 is the most widely accepted and used diagnostic manual for psychiatric disorders, and it specifies a minimum duration of 3 months.

**Correct Answer:** D. 3 months