The theory of tectonic plates explains that large convectional currents occuring in the mantle(as a result of magma) are the reasons plates,and so continents,are moved. Note movement occurs in the boundary in between the plates.
The answer to the fill in the blank is option B) Authentication
Passwords, tokens, and fingerprint scans are all examples of Authentication.
We use passwords, tokens and even fingerprints since they can be unique identifications and are usually seen as more secure.
In the above options, fingerprints are seen as the most secure form of authentication since everyone has unique fingerprints.
One of the earliest forms of authentication were time cards used as early as the 1950s and even unique keys and stamps used by early civilizations.