Identify X library function for line input and output in the following C code?

#include <stdio.h>
int X(char *s, FILE *iop)
{
    int c;
    while (c = *s++)
    putc(c, iop);
    return ferror(iop) ? EOF : 0;
}

A. stdio.h B. iostream.h C. fileio.h D. files.h

A. fopen() B. open() C. writefile() D. createfile()

A. A built-in data type for files B. A file descriptor C. A file pointer D. A file structure

A. Use the 'filestatus' variable B. Check the return value of fopen() C. Use the 'fileopen' function D. Check the file's size