Step-by-Step Explanation:
Analyze the Statements:
All doors are tables:
This means every door is a table, but not all tables are necessarily doors.
Diagrammatically:

No tables are chairs:
This means there is no overlap between tables and chairs.
Diagrammatically:

Evaluate the Conclusions:
No doors are chairs:
From the statements, all doors are tables, and no table is a chair. Hence, no door can be a chair.
Conclusion I is correct.
No chairs are doors:
Since no door is a chair (as shown above), it follows logically that no chair is a door.
Conclusion II is correct.
Some tables are doors:
From Statement 1, all doors are tables. This implies that some tables are indeed doors (all doors belong to the subset of tables).
Conclusion III is correct.
Final Answer:
(3) All three
All the conclusions (I, II, and III) are logically correct based on the given statements.