As exercise levels increase, which of the following physiological changes occurs in the respiratory system?
a.
the respiratory muscles shrink.
b.
the lungs expand in size.
c.
the trachea widens.
d.
the airways narrow.

The correct answer is B. The lungs expand in size

Explanation:

Exercise in an activity that actively involves muscles, due to the movement or effort of these during exercise. At the same time, this effort has an effect on other systems including the respiratory and the circulatory system and the effect in these increases based on the exercise level and the length of the exercise. In the case of the respiratory system, as we exercise this is required to get more oxygen for the muscles and due to this, during exercise, the lungs expand in size to take more oxygen from the air. Also, it is common the breathing rate increases to allow the body to have more oxygen. According to this, the change that occurs in the respiratory system as exercise levels increase is that the lungs expand in size.

wellness is an overall state of well-being. the quality or state of being healthy in body and mind, especially as the result of deliberate effort

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 .