Answer:
Hard Disk
Step-by-step explanation:
A very important part of a computer is the hard disk. It stores data and documents that users may have downloaded. Removing the hard disk could make the computer useless.
A mouse, keyboard, or pen drive can be easily removed.
A mouse and a pen drive are USB-connected devices and can be removed by simply unplugging the cable. A keyboard can be removed by simply taking off the keycaps. It is easily accessible.
-Chetan K