**Question:** Cardinal feature of antisocial personality -

A. Lack of empathy
B. Impulsivity
C. Lack of concern for others' feelings
D. Difficulty sustaining attention span

**Core Concept:**
Antisocial personality disorder (APD) is a mental health condition characterized by a pattern of disregard for and violation of the rights of others. It is classified under the Diagnostic and Statistical Manual of Mental Disorders (DSM) and is defined by specific criteria. In this context, the cardinal feature refers to the most essential characteristic of APD.

**Why the Correct Answer is Right:**
The correct answer, **B. Impulsivity**, highlights a key feature of antisocial personality. Impulsivity refers to a pattern of acting without thinking or considering consequences, which is evident in individuals with APD. This behavior contributes to their disregard for social norms and rules, leading to repeated violations of the rights of others.

**Why Each Wrong Option is Incorrect:**

A. **Lack of empathy (C. Lack of concern for others' feelings)**: While empathy and concern for others may be reduced in some cases, impulsivity is the primary feature that sets APD apart from other personality disorders.

B. **Difficulty sustaining attention span (D. Difficulty sustaining attention span)**: This option is incorrect as it does not directly relate to the core behavior pattern seen in antisocial personality. Attention span is not a defining feature of APD.

**Clinical Pearl:**
Understanding the cardinal feature of impulsivity in antisocial personality helps medical professionals in diagnosing and providing appropriate interventions for patients exhibiting such behavior. This information is crucial for medical students and professionals to have a comprehensive knowledge of mental health disorders and their characteristics.