See the explanation below
Explanation:
yum install httpd
systemctl --now enable httpd
systemctl status httpd
netstat -tunlp | grep 80
pkill <processname>
systemctl restart httpd
systemctl status httpd

Explanation
The command that would allow a user to choose a stronger password and set it on the existing SSH key file is ssh-keygen -p -f <keyfile>. This command uses the ssh-keygen tool, which is used to generate, manage, and convert authentication keys for SSH. The -p option stands for passphrase, and it allows the user to change or remove the passphrase of an existing private key file. The -f option specifies the filename of the key file. The command will prompt the user for the old passphrase, and then for the new passphrase twice.
The other options are not correct commands for changing the password of an SSH key file. The passwd command is used to change the password of a user account on a Linux system, not an SSH key file. The ssh command is used to log in to a remote system using SSH, not to change the password of an SSH key file. The pwgen command is used to generate random passwords, not to change the password of an SSH key file.
References: ssh-keygen(1) - Linux manual page; How To: Change Passphrase for SSH Private Key - Unix Tutorial

The output shows that the system has a total of 3736MB of memory, of which 3598MB is free. This indicates that the system has enough free memory space12.
Reference:
1(https://phoenixnap.com/kb/swap-space)
2(https://www.baeldung.com/linux/swap-space-use)

Explanation
The reason the firewall rules are not active is that the firewalld service is not enabled. This means that the service will not start automatically at boot time or after a system reload. To enable the firewalld service, the systems administrator needs to use the command sudo systemctl enable firewalld. This will create a symbolic link from the firewalld service file to the appropriate systemd target, such as multi-user.target. Enabling the service does not start it immediately, so the systems administrator also needs to use the command sudo systemctl start firewalld or sudo systemctl reload firewalld to activate the firewall rules.
The other options are not correct reasons for the firewall rules not being active. iptables is not conflicting with firewalld, because firewalld uses iptables as its backend by default. The wrong system target is not activated, because firewalld is independent of the system target and can be enabled for any target. FIREWALL_ARGS has no value assigned, but this is not a problem, because FIREWALL_ARGS is an optional environment variable that can be used to pass additional arguments to the firewalld daemon, such as --debug or --nofork. If FIREWALL_ARGS is empty or not defined, firewalld will use its default arguments. References: firewalld.service(8) - Linux manual page; firewall-cmd(1) - Linux manual page; systemctl(1) - Linux manual page

To create a symlink for /usr/local/bin/app-a, which was installed in /usr/local/share/app-a, the administrator can use the command ln -s /usr/local/share/app-a /usr/local/bin/app-a (A). This will create a symbolic link named /usr/local/bin/app-a that points to the original file /usr/local/share/app-a. The other commands will not create a symlink, but either move, copy, or synchronize the file. Reference:
[CompTIA Linux+ Study Guide], Chapter 3: Working with Files, Section: Creating Links
[How to Create Symbolic Links in Linux]