Explanation
The issue is caused by the lack of a default route defined in the /etc/sysconfig/network-scripts/ifcfg-enp0s3 file. A default route is a special route that specifies where to send packets that do not match any other routes in the routing table. Without a default route, the server will not be able to communicate with hosts outside its local network. The default route is usually configured with the GATEWAY option in the network interface configuration file. For example, to set the default gateway to 192.168.1.1, the file should contain:
GATEWAY=192.168.1.1
The other options are not causing the issue. The DNS address is not commented out in the configuration file, it is specified with the DNS1 option. The search entry in the /etc/resolv.conf file is correct, it specifies the domain name to append to unqualified hostnames. Wired connection 1 is online, as indicated by the ONBOOT=yes option and the output of ip link show enp0s3 command. References: Configuring IP Networking with nmcli; Configuring IP Networking with ifcfg Files

Explanation
This will prevent the file app.conf from being tracked by Git and uploaded to the repository. The .gitignore file is a special file that contains patterns of files and directories that Git should ignore. Any file that matches a pattern in the .gitignore file will not be staged, committed, or pushed to the remote repository. The .gitignore file should be placed in the root directory of the repository and committed along with the other files.
The other options are incorrect because:
A: Run git exclude app.conf
This is not a valid Git command. There is no such thing as git exclude. The closest thing is git update-index
--assume-unchanged, which tells Git to temporarily ignore changes to a file, but it does not prevent the file from being uploaded to the repository.
B: Run git stash app.conf
This will temporarily save the changes to the file app.conf in a stash, which is a hidden storage area for uncommitted changes. However, this does not prevent the file from being tracked by Git or uploaded to the repository. The file will still be part of the working tree and the index, and it will be restored when the stash is popped or applied.
C: Add app.conf to .exclude
This will have no effect, because Git does not recognize a file named .exclude. The only files that Git uses to ignore files are .gitignore, $GIT_DIR/info/exclude, and core.excludesFile.
References:
Git - gitignore Documentation
D:gitignore file - ignoring files in Git | Atlassian Git Tutorial
Ignoring files - GitHub Docs
[CompTIA Linux+ Certification Exam Objectives]

Explanation
The command mv .ssh/authorized_key .ssh/authorized_keys will resolve the issue and allow an SSH connection to be established without a password. The issue is caused by the incorrect file name of the authorized key file on the server. The file should be named authorized_keys, not authorized_key.
The mv command will rename the file and fix the issue. The other options are incorrect because they either do not affect the file name (restorecon or chmod) or do not restart the SSH service (systemctl). References: CompTIA Linux+ (XK0-005) Certification Study Guide, Chapter 13: Managing Network Services, page 410.

The command that would ensure the server is set to runlevel 5 is systemctl isolate graphical.target. This command will change the current target (or runlevel) of systemd to graphical.target, which is equivalent to runlevel 5 in SysV init systems. Graphical.target means that the system will start with a graphical user interface (GUI) and all services required for it.
The other options are not correct commands for setting the server to runlevel 5. The systemctl isolate multi-user.target command will change the current target to multi-user.target, which is equivalent to runlevel 3 in SysV init systems. Multi-user.target means that the system will start with multiple user logins and networking, but without a GUI. The systemctl isolate network.target command will change the current target to network.target, which is not a real runlevel but a synchronization point for network-related services. Network.target means that network functionality should be available, but does not specify whether it should be started before or after it. The systemctl isolate basic.target command will change the current target to basic.target, which is also not a real runlevel but a synchronization point for basic system services. Basic.target means that all essential services should be started, but does not specify whether it should be started before or after it. Reference: systemd System and Service Manager; systemd.special(7) - Linux manual page