Which device would best verify the identity of a user on a laptop?

A fingerprint scanner is the most effective device for verifying the identity of a user on a laptop because it uses biometric authentication. Biometric authentication relies on unique physical characteristics of an individual—in this case, their fingerprint—to grant access. This method provides a higher level of security compared to traditional passwords or PINs, as fingerprints are unique to each individual and nearly impossible to replicate.

The other options do not serve the primary purpose of identity verification. A webcam could potentially allow for facial recognition, but this is less common and less secure than fingerprint scanning. An external hard drive and a USB flash drive are storage devices that do not have any inherent capability to authenticate a user’s identity and are unrelated to the process of verifying who is accessing the laptop. Thus, when considering the best device for user identity verification on a laptop, the fingerprint scanner stands out for its effectiveness and security features.