b) Mark and Helen are two new sysadmins hired by ITS to administer their Unix systems. i. Explain the strategy used by Unix systems to support extended access control lists. ii. The owner and group classes have read and write permissions on the /etc/passwd file. The other class doesn't have any permission to the file. Mark and Helen need read and write permissions to the file. Describe the extended ACLs for this system. c) Explain how ITS can use password file access control to thwart a password attack in their systems