Which of the following is the most commonly used check on something you know?

A.
One time password

B.
Login phrase

C.
Retinal

D.
Password

Explanation:
Passwords even though they are always mentioned as being unsecured, necessary evils,
that put your infrastructure at risk, are still commonly used and will probably be used

for quite a few years. Good passwords can provide you with a good first line of
defense. Passwords are based on something the user knows. They are used to authenticate
users before they can access specific resources.