Statements : All trains are buses. No room is bus. All boats are rooms. Conclusions : I. No boat is train. II. No bus is boat. III. No train is room.

The correct answer is $\boxed{\text{E}}$.

Statement 1: All trains are buses.

Statement 2: No room is bus.

Statement 3: All boats are rooms.

Conclusion 1: No boat is train.

This conclusion follows from Statement 1 and Statement 2. If all trains are buses, and no room is a bus, then no room can be a train.

Conclusion 2: No bus is boat.

This conclusion follows from Statement 2 and Statement 3. If no room is a bus, and all boats are rooms, then no bus can be a boat.

Conclusion 3: No train is room.

This conclusion follows from Statement 1 and Statement 3. If all trains are buses, and all boats are rooms, then no train can be a room.

Therefore, all three conclusions follow.