Final answer:
The concept of vulnerability in research proposed by NBAC includes features such as low socioeconomic status, cognitive impairment, and age. Gender, however, was not included.
Step-by-step explanation:
The concept of vulnerability in research proposed by NBAC (National Bioethics Advisory Commission) includes several features that can potentially lead to vulnerability. These features include low socioeconomic status, cognitive impairment, and age. However, gender was not included as a factor that can lead to vulnerability.