The correct answer is hardware.
Keyboard, mouse, and tower case are examples of hardware.
Hardware are known as the physical elements or component of the computer, other examples include to mention but a few monitors, the central processing unit (CPU), joystick, hard disk drive.
All other options are wrong.
Softwares are programmed instructions stored in the computer system for execution by the processor examples are operating systems, firmware, drivers etc.
A computer is a device that accesses and process data to give information.
An application is a software program on a computer system.