Explanation : This is an AEE type syllogism where
premises 'All X are Y'(A), and 'No Y are
Z'(E), lead to the conclusion 'No Z are
X' (E). So, the conclusion of the given
premises will be 'No book is diary'.
Conversion yields an equivalent proposition
(and is hence a valid inference). Option (d)
'No diary is book' is the converse of this
conclusion; hence, valid. Also, option (c)
'No book is copy' is the converse of the