Answer: A. A method of access control that allows a user to log on to a system and gain access to other resources within the network via the initial logon
Explanation: key distribution center ( KDC) is a system that is used to provide access to a particular network user who shares data which are either private or regarded as sensitive.
It is a form of encryption that allows multiple system within the same network through the use of uniquely secured tickets used to setup a secure connection which gives room for data to be shared.
KDC makes use of cryptographic techniques to prove the validity of a user and grants a ticket permission access. The user present the ticket of permission to the system which then validates it and grant access to the user.
Example of security system that adopts KDC include kerberos.