Statements: Some documents are files.
All books are folders.
No file is a folder.
Conclusions: I. No folder is a file.
II. All folders are documents.
III. No book is a file.
No file is a folder (E) ⇒ conversion⇒ No folder is a file (E). Hence conclusion I follows. Some documents are files (I) + No file is a folder (E) ⇒ Some documents are not folders(O). Hence conclusion II does not follow. All books are folders (A) + [No file is a folder (E)] ⇒ conversion⇒ No folder is a file (E) ⇒ No book is a file (E). Hence conclusion III follows.