Which of the following diagnostic criteria most clearly distinguishes autism spectrum disorder (ASD) from social communication disorder?

The correct diagnostic criterion that most clearly distinguishes autism spectrum disorder (ASD) from social communication disorder is the presence of restricted and repetitive behavior patterns. This characteristic is a key element of ASD diagnosis and differentiates it from social communication disorder, where such behaviors are not a defining feature.

ASD is characterized not only by challenges in social communication but also by specific patterns of behavior, such as insistence on sameness, highly focused interests, or repetitive motor movements. In contrast, individuals with social communication disorder primarily exhibit difficulties in social language use and interactions without the accompanying repetitive behaviors that are hallmarks of ASD.

While delayed language acquisition and difficulties with conversational rules may be present in both conditions, they do not provide a clear distinction. Limited comprehension of abstract language can also occur in both disorders, but it is the restricted and repetitive behaviors that serve as a defining aspect of ASD. Therefore, this criterion is essential for differentiating ASD from social communication disorder.