The correct answer is: Only I and II follow.
The first statement is “Some bricks are trees.” This means that there is at least one brick that is also a tree. The second statement is “All trees are pens.” This means that every tree is a pen. The third statement is “All pens are boats.” This means that every pen is a boat.
The first conclusion is “Some boats are bricks.” This conclusion does not follow from the premises. The premises only say that some bricks are trees, and that all trees are pens. They do not say anything about boats. Therefore, it is possible that there are no boats that are bricks.
The second conclusion is “Some pens are bricks.” This conclusion does follow from the premises. The premises say that some bricks are trees, and that all trees are pens. Therefore, there must be at least one pen that is also a brick.
The third conclusion is “Some trees are bricks.” This conclusion does follow from the premises. The premises say that some bricks are trees, and that all trees are pens. Therefore, there must be at least one tree that is also a brick.
The fourth conclusion is “Some bricks are boats.” This conclusion does not follow from the premises. The premises only say that some bricks are trees, and that all trees are pens. They do not say anything about boats. Therefore, it is possible that there are no bricks that are boats.
In conclusion, only the first and second conclusions follow from the premises.