Final answer:
The primary factor contributing to the advantage of standing a good distance away from the camera in retina scans is the unique vascular patterns in the retina.
Step-by-step explanation:
The primary factor contributing to the advantage of being able to stand a good distance away from the camera and still produce a viable image in retina scans is the unique vascular patterns in the retina.
The retina contains a network of blood vessels that exhibit distinct patterns for each individual. These patterns do not change with distance, allowing the camera to capture a clear image even when the user is far away.
This advantage is not dependent on infrared radiation, high-resolution cameras, or facial recognition algorithms.