In a Public Key Infrastructure, how are public keys published?

A.
They are sent via e-mail.

B.
Through digital certificates.

C.
They are sent by owners.

D.
They are not published.

Explanation:
The main role of the CA is to digitally sign and publish the public key bound to a given user by issuing digital
certificates which certifies the ownership of a public key by the named subject of the certificate.
Incorrect Options:
A: The main role of the CA is to digitally sign and publish the public key bound to a given user, so it is not sent
via e-mail.
C: The main role of the CA is to digitally sign and publish the public key bound to a given user, so they are not
sent by owners.
D: The main role of the CA is to digitally sign and publish the public key bound to a given user. Clearly they are
published.

https://en.wikipedia.org/wiki/Public_key_infrastructure
https://en.wikipedia.org/wiki/Certificate_authority