What is a public key infrastructure?

A$.$ It is a structure that enables e$-$mail.

B$.$ It is a structure that provides all the necessary components to enable users and entities to communicate in a secure and a predictable manner.

C$.$ It is a structure that enables secure chat rooms.

D$.$ It is another term for digital signature.

What is a registration authority $($RA$)?$

A$.$ An entity that requires proof of identity from the individual requesting a certificate.

B$.$ An entity that generates a digitally signed identification certificate.

C$.$ A centralized directory in which the registered certificate is stored.

D$.$ An entity that generates electronic credentials.