Question

Statements: All doors are buses. All buses are leaves. No leaf is a flower.
Conclusions:
I. No flower is a door.
II. No flower is a bus.
III. Some leaves are doors.
IV. Some leaves are buses.

• A. None follows
• B. Only I and II follow
• C. Only II and III follow
• D. Only II, III and IV follow
• E. All follow

Answer 1

The correct option is E All follow

IV is the converse of the second premise and so it holds.
All doors are buses. All buses are leaves.
Since both the premises are universal and affirmative, the conclusion must be universal affirmative and should not contain the middle term. So, it follows that 'All doors are leaves'. III is the converse of this conclusion and so it holds.
All buses are leaves. No leaf is a flower.
Since both the premises are universal and one premise is negative, the conclusion must be universal negative and should not contain the middle term. So, it follows that 'No bus is flower'. II is the converse of this conclusion and so it holds.
All doors are buses. No bus is flower.
As discussed above, it follows that 'No door is flower'. I is the converse of this conclusion and so it also holds.