**Core Concept**
Binge eating disorder and bulimia nervosa are two distinct eating disorders with different characteristics and underlying pathophysiology. Binge eating disorder is characterized by recurrent episodes of eating large quantities of food in a short period, accompanied by feelings of guilt, shame, and distress. In contrast, bulimia nervosa involves recurrent episodes of binge eating followed by compensatory behaviors such as self-induced vomiting, laxatives, or excessive exercise.

**Why the Correct Answer is Right**
The correct answer is related to the presence of purging behaviors in bulimia nervosa. Individuals with bulimia nervosa often engage in purging behaviors to compensate for the calories consumed during binge eating episodes. This is in contrast to individuals with binge eating disorder, who do not engage in regular purging behaviors. The key difference lies in the compensatory behaviors that follow binge eating episodes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not specific to the comparison between binge eating disorder and bulimia nervosa. Both disorders involve binge eating episodes, but the key difference lies in the compensatory behaviors.

**Option B:** This option is incorrect because it is not directly related to the comparison between the two disorders. While mood disorders can co-occur with both binge eating disorder and bulimia nervosa, they are not the primary distinguishing feature between the two conditions.

**Option C:** This option is incorrect because it is not specific to the comparison between binge eating disorder and bulimia nervosa. Both disorders involve emotional dysregulation and feelings of guilt or shame, but the key difference lies in the compensatory behaviors.

**Option D:** This option is incorrect because it is not directly related to the comparison between the two disorders. While both disorders involve food-related behaviors, the key difference lies in the presence or absence of purging behaviors.

**Clinical Pearl / High-Yield Fact**
A key distinguishing feature between binge eating disorder and bulimia nervosa is the presence or absence of purging behaviors. Individuals with bulimia nervosa often engage in regular purging behaviors to compensate for the calories consumed during binge eating episodes, whereas individuals with binge eating disorder do not engage in regular purging behaviors.

**Correct Answer:** D.