Which of the following statements are correct? (1) Organ systems in different animal groups show various patterns of complexity (2) The digestive system in platyhelminthes has a single opening serving as both mouth and anus, and is therefore complete (3) In open type of circulatory system, blood is pumped out of the heart and cells are directly bathed in it (4) In closed type, blood circulates through vessels (arteries, veins and capillaries)