Which of the following is a characteristic of Angelman syndrome?

Angelman syndrome is a neurodevelopmental disorder that primarily affects the nervous system and is characterized by specific behavioral and physical features. One of the hallmark characteristics of this condition is severe mental retardation, which reflects significant cognitive impairment. Individuals with Angelman syndrome typically exhibit developmental delays, leading to severe intellectual disability.

In addition to cognitive challenges, seizures are also a common feature of Angelman syndrome. These seizures can vary in type and frequency but are a crucial aspect of the condition. Therefore, the presence of severe mental retardation and seizures is a defining feature of Angelman syndrome, making this the correct answer.

The other options, while they may describe various medical conditions or syndromes, do not specifically align with the key characteristics of Angelman syndrome. For instance, severe obesity is not a recognized feature of this condition, as affected individuals often have a different physical stature due to other anomalies. Small hands and feet can occur in various genetic syndromes but are not distinctive traits of Angelman syndrome specifically. Neonatal hypotonia does present in many cases, but it is not as defining as the cognitive impairments and seizures that are prominent in Angelman syndrome.