What is the primary effect of invoking a file-close system call on an open…

1. A.

   It renames the file on disk to signal that it's no longer in use.

2. B.

   It flushes any buffered output, releases kernel resources, and invalidates the descriptor for further I/O.

3. C.

   It immediately frees the memory occupied by the file's data in user space.

4. D.

   It deletes the file from the file system once all operations are done.

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