The administrator should place the public keys for the server in the ~/.ssh/authorized_keys file. The SSH (Secure Shell) protocol is a method for establishing secure and encrypted connections between remote systems. The SSH protocol supports two types of authentication: password-based and key-based. Password-based authentication requires the user to enter the password of the remote system every time they connect. Key-based authentication requires the user to generate a pair of cryptographic keys: a public key and a private key. The public key is stored on the remote system, while the private key is kept on the local system. The public key and the private key are mathematically related, but not identical. The SSH protocol uses the keys to verify the identity of the user and establish a secure connection without requiring a password. The ~/.ssh/authorized_keys file is a file that contains the public keys of the users who are allowed to connect to the remote system using key-based authentication. The administrator should place the public keys for the server in this file, one per line, and set the appropriate permissions for the file. The administrator should also configure the SSH server to enable key-based authentication by editing the /etc/ssh/sshd_config file and setting the option PasswordAuthentication to no. The administrator should place the public keys for the server in the ~/.ssh/authorized_keys file. This is the correct answer to the question. The other options are incorrect because they are not the standard locations for the public keys for the server (~/.sshd/authkeys, ~/.ssh/keys, or ~/.ssh/keyauth). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 17: Implementing Basic Security, page 513.