Not all user-defined functions must have a "return statement? Select one: True False One of the following is not an input device. Select one O a. Scanner b. Mic c. Digital Camera Od Printer After the declaration of the outf as output file stream what happens when you execute the following C++ statement outlopen ("ABC.txt"); Select one ca. Replaces the existing file ABCititor create a new one b. The output file will be used for input instead e Retumso doptos only an existing file ABC.txt Will Fee