The correct answer is A. tee.
Tee is a command-line utility that copies standard input to one or more files and to standard output. It is often used to save the output of a command to a file, as well as display it on the terminal.
For example, the following command will save the output of the ls command to a file called output.txt, as well as display it on the terminal:
ls | tee output.txt
The tee command can also be used to concatenate multiple files together. For example, the following command will create a new file called combined.txt that contains the contents of the files file1.txt and file2.txt:
cat file1.txt file2.txt | tee combined.txt
The tee command is a powerful tool that can be used for a variety of purposes. It is often used in conjunction with other commands to save the output of a command to a file, or to concatenate multiple files together.
The other options are incorrect for the following reasons:
- B. grep is a command-line utility that searches for lines of text that match a regular expression. It does not save the output of a command to a file.
- C. cat is a command-line utility that concatenates and prints the contents of files. It does not save the output of a command to a file.
- D. more is a command-line utility that paginates the output of a command. It does not save the output of a command to a file.
- E. None of the above is the correct answer.