Most of the normal microbiota of the digestive system are found in the

Large intestine.

Explanation:

There are some common misconception that all the bacteria can cause disease. They play an important role in the digestion of food.

The large intestines is the home for many different types of bacteria which helps in the absorption, excretion and catalysis of undigested food.

There are many types of prokaryotic and eukaryotic bacteria found in large intestine such as Methanogens, Bifidobacterium,Enterococcus, Clostridium et cetera.

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.