Final answer:
The level of intellectual disability describing individuals with IQs ranging from 20 to 40 is the profound level. This is the most severe subtype of intellectual disability, requiring significant support and supervision for daily activities.
Step-by-step explanation:
Individuals with IQs ranging from 20 to 40 are described as having a profound level of intellectual disability, according to the Diagnostic and Statistical Manual of Psychological Disorders (DSM-5) criteria. This level of intellectual disability is characterized by significant limitations in both cognitive functioning and adaptive behaviors, such as communication, social skills, and self-care. Those with profound intellectual disability often require close supervision and extensive support with day-to-day activities. It is the most severe subtype out of the four levels of intellectual disability defined in the DSM-5, with the other three being mild, moderate, and severe.