Two 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 follows from the statements:
Statements:
Some books are copies.
Some copies are diaries.
Conclusions:

I. Some books are diaries

II. No copies are books.
III. No diary is a book. ​​

​Some books are copies.
Some copies are diaries.

Does NOT follow

Reason:
“Some books are copies” and “some copies are diaries”
The same copies may not be common
So no definite link between books and diaries

Because:
“Some books are copies” → means some copies ARE books

Does NOT follow

No direct relation is given between diary and book

Between:

I: Some books are diaries

III: No diary is a book

These are contradictory (complementary pair)
One must be true, but we cannot say which.

Conclusion I and III are complementary pairs.

so, Either conclusion I or III follows