Which of the following best describes a dependent adult?

The definition of a dependent adult is best represented by the description of a person who is aged 18 to 64 and unable to care for themselves due to certain conditions. This categorization acknowledges that dependency can arise from various physical or mental impairments, as well as developmental disabilities that may inhibit an individual's ability to perform daily self-care tasks.

While individuals over 65 needing assistance and minors requiring guardianship reflect different types of dependency, they do not capture the broader range of dependent adults who fall into the 18 to 64 age group. Thus, it is critical to distinguish that dependency is not solely about age but also about the individual's capacity to care for themselves, which is highlighted in the correct specification.