I believe that the right answer is Heat energy
Your circulatory system consists of your heart, blood vessels and blood, and is responsible for transporting life-giving oxygen throughout your body. When you exercise, your body's need for oxygen increases; the harder you work out, the more oxygen your body demands.
DNA, or deoxyribonucleic acid, is a long chain molecule that plays a central role in life on earth. The information encoded in strands of DNA controls the genetic makeup of organisms. The DNA molecule has a backbone of sugars and phosphate groups off of which hang simpler units called nucleotide bases.
