I believe the answer is a.
The answer is muscular strength
Muscular Strength- The greatest force that can be produced by a muscle or a group of muscles
The main factor that controls the rate of breathing is..
A.) concentration of carbon dioxide.
If we think about it.. When we breath in oxygen, right away it enters your lungs and turns into carbon dioxide. Well since your lungs need to process oxygen and bring oxygen into the blood stream. Then as soon as the oxygen comes inside (inhale) the oxygen turns into carbon dioxide and you breath it out (exhale) to get a new oxygen load.
Makes sense? lol
Good Luck! :)
A person with clinical depression will experience at least four signs of the disorder for at least two weeks.
The symptoms showing the illness may include: Trouble in concentrating or remembering small details, and making decisions in everyday life.
Also you'll fatigued through out the day, you will get feelings of guilt, worthlessness, and helplessness.
It may also include Insomnia, early-morning wakefulness, or sleeping too much.
Also you lose your focus and there is a loss of interest in things once pleasurable, including sex.
