How can natural selection result
in the adaptation of a population?

The traits of those who died before reproducing deemed "undisireable" (like a tale,scales,wings etc.) would have died out as they would not have had the opportunity to pass on these genes. Those of the same species who survived due to a lack of the "undisireable" trait would have the opportunity to reproduce and pass on the complete lack of the trait itself or a smaller version of the trait. This is what enables different species to adapt to live in different enviorments,you can observe this in different species that share a common ancestor.

Explanation: It's kind of in the answer

this protocol describes a detailed procedure for intracellular flow cytometry staining.

hypoxemia refers to a below usual concentration of oxygen in the blood, mainly in the arteries. hypoxemia is an indication of an issue associated with circulation or breathing and may lead to various symptoms like shortness of breath.  

the condition is identified by determining the level of oxygen in the blood sample obtained from an artery. it can also be predicted by determining the oxygen saturation of the blood with the application of a pulse oximeter.  

the normal arterial oxygen is about 75 to 100 mm hg. the values underneath 60 mm hg is generally considered with the requirement for supplemental oxygen. the normal pulse oximeter readings generally range between 95 to 100 percent. the values under 90 percent are regarded as low.  

in the given case, the oxygen saturation is measured at 93 percent, hence, there is no need to administer oxygen, that is, one should withhold oxygen.