What kind of certificate is used to validate a user identity?

A.
Public key certificate

B.
Attribute certificate

C.
Root certificate

D.
Code signing certificate

Explanation:
In cryptography, a public key certificate (or identity certificate) is an electronic document which incorporates a
digital signature to bind together a public key with an identity — information such as the name of a person or an
organization, their address, and so forth. The certificate can be used to verify that a public key belongs to an
individual.
Incorrect Answers:
B: In computer security, an authorization certificate (also known as an attribute certificate) is a digital document
that describes a written permission from the issuer to use a service or a resource that the issuer controls or has
access to use.
C: A root certificate is an unsigned or a self-signed public key certificate that identifies the Root Certificate
Authority (CA).
D: Code signing digitally signs executables and scripts to verify the software author and guarantee that the
code has not been changed or tainted since it was signed by use of a cryptographic hash.

http://en.wikipedia.org/wiki/Attribute_certificate
http://en.wikipedia.org/wiki/Public_key_certificate
https://en.wikipedia.org/wiki/Root_certificate
https://en.wikipedia.org/wiki/Code_signing