Explanation:
The certificate authority maintains a directory of digital certificates for the reference of those receiving them, it manages the certificate life cycle, including certificate directory maintenance and certificate revocation list maintenance and publication. Choice A is not correct because a registration authority is an optional entity that is responsible for the administrative tasks associated with registering the end entity that is the subject of the certificate issued by the CA. Choice C is incorrect since a CRL is an instrument for checking the continued validity of the certificates for which the CA has responsibility. Choice D is incorrect because a certification practice statement is a detailed set of rules governing the certificate authority’s operations.