The command ls can be used to display the inode number of a given file by using the -i option. The inode number is a unique identifier for each file in a Linux file system. It contains information about the file's attributes, such as size, permissions, ownership, timestamps, and location on the disk12. For example, ls -i file.
txt will show the inode number of the file file.txt in the current directory. The command inode does not exist in Linux. The command ln can be used to create links to files, but not to display their inode numbers. The command cp can be used to copy files, but not to display their inode numbers3. References: 1: What is an Inode in Linux? 2: Understanding Linux File System Inodes 3: Linux Commands Cheat Sheet

The quiet kernel parameter instructs the kernel to suppress most boot messages, except for critical errors12. The quiet parameter can be added to the GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc
/default/grub file and then run sudo update-grub to apply the changes3. The quiet parameter can also be used in combination with other parameters, such as splash, to enable a graphical boot screen4.
The other options in the question are not valid or do not have the same functionality as the quiet parameter:
* silent: There is no such kernel parameter in Linux.
* verbose=0: This parameter is used to set the verbosity level of the kernel messages, but it does not suppress them completely. The valid values for this parameter are from 0 (quiet) to 7 (debug)5.
* nomesg: This parameter is used to disable all kernel messages on the console, including the emergency ones. This parameter is not recommended for normal use, as it can hide critical errors and prevent troubleshooting.
:
1: Getting the Kernel Command-Line Parameters | Baeldung on Linux 2: How to mute kernel messages at startup in Arch Linux? 3: boot - How to turn off the filesystem check message which occures while booting - Ask Ubuntu 4: [How to enable a graphical boot screen on Ubuntu 18.04 LTS - LinuxConfig.org] 5: [Kernel parameters - ArchWiki] : [Linux Kernel Parameters - SysTutorials]

This command creates a hard link to a.txt with the name c.txt. The new file c.txt will have the same inode number as a.txt (Inode 525385).
A hard link is a directory entry that points to the same data blocks as another file. A hard link is indistinguishable from the original file, and it shares the same inode number, permissions, ownership, and timestamps. A hard link can only be created within the same file system, and it cannot link to directories or special files. A hard link increases the link count of the file, which is the number of directory entries that refer to the file. The link count can be seen by using the ls -l command. The file is only deleted when the link count reaches zero, which means that all the hard links to the file are removed.
The ln command is used to create hard links or symbolic links. The syntax of the ln command is:
ln [options] source target
The source is the name of the existing file, and the target is the name of the new link. By default, the ln command creates a hard link, unless the -s option is used to create a symbolic link. A symbolic link is a special file that contains the path to another file or directory. A symbolic link is different from a hard link, as it has its own inode number, permissions, ownership, and timestamps. A symbolic link can link to any file or directory, even across file systems, and it does not affect the link count of the file. A symbolic link can be identified by the ls -l command, as it shows the link name followed by an arrow and the target name.
For example, to create a hard link to a.txt with the name c.txt, use the following command:
ln a.txt c.txt
This command will create a new file c.txt that has the same inode number as a.txt (Inode 525385). The output of the ls -i command will show something like:
525385 a.txt 525385 c.txt
To create a symbolic link to a.txt with the name b.txt, use the following command:
ln -s a.txt b.txt
This command will create a new file b.txt that has a different inode number than a.txt (Inode 526053), and contains the path to a.txt. The output of the ls -i command will show something like:
525385 a.txt 526053 b.txt -> a.txt
References:
Linux Hard and Soft Links - Linuxize
ln(1) - Linux manual page
How to Create Hard and Symbolic Links in Linux - How-To Geek