You can improve or maintain how well heart and lungs work by applying the FITT principle for a
muscular endurance
b
muscular strength
c
flexibility
d
cardiorespiratory endurance

The correct answer is D. It is the only option that improves heart and lung capacity.

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

                                                        water

a colorless, transparent, odorless, tasteless liquid that forms the seas, lakes, rivers, and rain and is the basis of the fluids of living organisms.

                                                        halon  

any of a number of unreactive gaseous compounds of carbon with bromine and other halogens, used in fire extinguishers, but now known to damage the ozone layer.

                                                  dry chemical

extinguishing agent used on class a, class b, and class c fires.

                                                  carbon dioxide

a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. it is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.