Ineed on the food chain:
consider the following food chain:
- grass absorbs sunlight
- grasshopper eats grass
- snake eats grasshopper
- hawk eats snake

The food chain that is described in the question is called Grazing food chain.

Explanation:

Grazing food chain  is a type of food chain that contain producers at the  lowest tropic level.The producers can manufacture their own food by photosynthesis process. Here grass act as producers.

                       The second topic level of grazing food chain contain primary consumers which consume producer. Here grasshopper eat grass,as a result grasshopper act as primary consumers or herbivores

           The third tropic level of grazing food chain contain secondary consumers that feed on primary consumers. Here snake eats grasshopper,as a result snake act as secondary consumers or primary carnivores.

         The highest tropic level of grazing food chain contain tertiary consumers  or secondary carnivores.Hawk eats snake,as a result hawk act as Tertiary consumers or secondary carnivores.

b.have there own function.

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.