Which of these is a function of the circulatory system?

transport of oxygen

digestion of food

production of hormones

reflex response

transport of oxygen. Circulatory system transports oxygen to different parts of the body through red blood cells. Digestion of food is not the right answer because it is the role of the digestive system. The endocrine system facilitates production of hormones and reflex response is made possible by the nervous system, so the last two are also not the right answers.