1. The disadvantage of High-Level Disk I/O functions is that the programmer has to manage the buffers.
2. If a file is opened for reading it is necessary that the file must exist.
3. If a file opened for writing already exists its contents would be overwritten.
4. For opening a file in append mode it is necessary that the file should exist.
False: If the file does not exist, so it creates a new file.