$4.\_\_$A$\_\_$ is the term for the physical parts of a computer. In contrast, $\_\_$B$\_\_$ is the term for the programs $($the $0\text{'}$s and $1\text{'}$s$)$ that instruct the computer what to do$.$

A: Software, B: Hardware

A: Keyboard, B: Mouse

A: Hardware, B: Software

A: Mac OS$,$ B: PC