since you have not provided the options here i am going to give you general overview about hormone.hormone are actually the part of endocrine system in our body and produced by the endocrine glands. the hormones act like a chemical messenger within human body. once produce by the glands they travel through the blood stream and reach at specific or target tissue and organs which result in control of our body function. the hormones are specific in their work and work on only the targeted tissue or organ . with the of hormone endocrine system regulate the heart rate , metabolism, our mood and growth as well as the development and even the sleeping cycle etc. they actually are the messenger for body cell and organs .
The amount of oxygen that is actually used by the body during the rest or a hand workout is determined by the heart rate, the stroke volume, and the amount of a. blood circulating in the vascular system b. oxygen removed from the vascular system c. oxygen provided to the vascular system d. blood that individual has in the body e. hemoglobin in the red blood cells