1. Describe the operating system's two modes of operation. (5 points) 2. Use vi to create a text file and type the text that includes your name, the semester, and the date. An example is like: This is John Smith. The semester is Fall 2022. Today is 9/16/2022. Then save the file and quit vi. In the prompt line, use the command cat to display the text file's content. Take a sereenshot (which should include your command lines and the execution result). You can insert the screenshot image in your Word document for submission. (20 points) 3. Write a C program that counts the number of non white-space characters in an input text file. Program takes as command argument(s) the name of the input file (and the output file with option f. Based on the option flags, it displays the output on the standard output, or writes the output to an output file. (25 points) The command format is as follows: command if inputfile outputfile or, command =s inputfile - f indicates writing to an output file; s indicates displaying the output on the screen. Also notice the errors caused by incomplete arguments. Be sure to comment your program, including: (1) The name of the author of the program (your name) and the date it was written, (2) a concise description of what the program does, (3) a clear description of its limitations if it does not meet all specifications, and (4) explanation for critical code and data declarations. The same should also be done for each function written in the program. You will lose some points if the above comment part is missing. Submit the source code and the screenshot for the execution result. You can insert them in the Word document for submission