Why do you need "using System.IO;$"$ in the program which reads data from a file?

Why do you need "using System.IO;$"$ in the program which reads data from a file?

The data file is stored in the "System.IO$"$

StreamReader class is in the "System.IO$"$ namespace$/$package$.$

The "System.IO$"$ allows the program to take data inputs from the keyboard.

The "System.IO$"$ allows the program to display data on the screen.