Q. An essential difference between the operating system that runs a typical desktop computer and the operating system that runs a typical PDA is that .......

• (A) the desktop OS has a graphical user interface whereas the PDA OS does not.
• (B) the desktop OS can run several programs simultaneously whereas the PDA OS cannot.
• (C) the desktop OS manages hardware resources whereas the PDA OS does not.
• (D) the desktop computer has an OS whereas a PDA does not.