Final answer:
The correct statement is B: Fingerprint scanners are the most widely used biometric authentication method. They are preferred for their balance between cost, convenience, and security.
Step-by-step explanation:
Regarding the various tools of biometric authentication and their capabilities/limitations, the accurate statement is that Fingerprint scanners are the most widely used biometric authentication method. Fingerprint technology is popular due to its ease of use, cost-effectiveness, and relatively high level of security. Unlike retinal scanning, which can be deemed more intrusive, fingerprint scanning involves simply placing a finger on a sensor.
Retinal scanning is actually considered to be more intrusive than iris scanning, not less, because retinal scanning involves shining a bright light into the eye to capture the unique patterns of the retina, which can be uncomfortable for the user. Sensor modules refer to a wide range of sensing devices and do not specifically pertain to a preferred method of biometric authentication. As for the cost, fingerprint scanners tend to be affordable, not more expensive as suggested in one option, and the technology behind them is well-established and not overly complex.