Three statements are given followed by three conclusions numbered I, II and III.
Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusions logically follow(s) from the statements.

Statements:
No file is a folder.
Some files are PDFs.
All files are Excel sheets.

Conclusions:
I. Some PDFs are folders.
II. Some Excel sheets are folders.
III. Some PDFs are Excel sheets.