To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) (1) Opens the external file for output and checks the file status code - This option is correct. The function of EF1OPENO is to open the external file for output and check the file status code. This function is typically used when you want to write data to a file.
Option B) (2) The main program, which calls all the subprograms and then verifies the contents of a record area - This option is incorrect. This description does not match the function of EF1OPENO.
Option C) (3) Opens the external file for input and checks the file status code - This option is incorrect. The function of EF1OPENO is to open the file for output, not input.
Option D) (4) Reads a record from the external file and checks the file status code - This option is incorrect. The function of EF1OPENO is to open the file for output, not read records.
The correct answer is A) (1) Opens the external file for output and checks the file status code. This option is correct because it accurately describes the function of EF1OPENO.