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.
• E. None of these