In this question are given four statements followed by five conclusions, one of which deﬁnitely does not logically follow (or is not a possibility of occurrence) from the given statements. That conclusion is your answer.
(Note: You have to take the four given statements to be true).
=> All references are mails.
=>All mentions are references.
=>All comments are mentions.
=>No mail is a declaration.
1) No reference is a declaration.
2) All comments are mails.
3) No mention‘ is a declaration.
4) All declarations being comments is a possibility.
5) At least some mails are mentions.