Which is a common barrier to healthcare access for vulnerable populations?

Lack of insurance is a significant barrier to healthcare access for vulnerable populations because it directly affects individuals' ability to afford medical care. Without health insurance, individuals may delay seeking necessary treatments, have difficulty accessing preventive services, or be unable to afford medications. This lack of access can lead to more severe health issues over time, as individuals may only seek care in crisis situations when they have no other options.

While limited access to technology can hinder health information or telehealth services, it is not as universally impactful as lack of insurance. High levels of education and excessive wealth are generally associated with increased health literacy and resources, facilitating better healthcare access rather than posing barriers. Therefore, the lack of insurance stands out as a critical barrier that can disproportionally affect those in vulnerable populations, making it the correct choice in this context.