Given statements:
1. All boys need books.
2. All girls need books.
3. Punjabis are girls.
4. Some Punjabis need books.
5. All boys are girls. 6. Some boys are Punjabis.
The set of statements is:
Treating "All A are B" as a mathematical inclusion relation, written \( A \subseteq B \), lets us check each option using the transitive property of inclusion: if \( A \subseteq B \) and \( B \subseteq C \), then it always follows that \( A \subseteq C \). Let's test each option against this property:
Only the fourth grouping satisfies the transitive property of inclusion in full, where the third statement is the direct mathematical consequence of chaining the first two.
Therefore, the correct answer is 5, 2, 1.