Answer: The digestive system breaks down food into nutrients that are transported by the circulatory system.
Step-by-step explanation:
An organ system includes the organs which are linked to one another to perform a physiological function in the body of the organism. The digestion is a complex process in which the food is being broken down into sub-components so that it can be assimilated in the body. The digestive system involves the multiple organs like mouth, esophagus, stomach, intestines and others. The food being digested is absorbed in the bloodstream, which circulate in the vital organs of the body like lungs, heart, vascular system hence, the blood becomes the part of the circulatory system.
Thus it can be said that the argument of children that the two systems are related is justified by the digestive and circulatory system of the body.