Flexibility is the capacity to move a joint through its full range of motion.
a. true
b. false

True.
as flexibility is  the ability of a joint to move through its normal, full range of motion.
flexibility exercises should be incorporated into the overall fitness program sufficient to develop and maintain range of motion
stretching muscles is recognized as the easiest and safest way to maintain and/or increase flexibility.

They carry out the exchange of gases as we breathe ( oxygen and carbon dioxide).