The main producers in aquatic environments are a. phytoplankton b. zooplankton c. kelp d. fish

The correct answer is a. phytoplankton.

Phytoplankton or microalgae are unicellular photosynthetic organisms. Dinoflagellates and diatoms are the two classes of phytoplankton. They float on the surface of the ocean water and are primary producer in the ocean. They provide food for marine animals such as whales, shrimp, snails and jellyfish. In presence of many nutrients in the ocean, phytoplankton may grow out of control to form harmful algal blooms.

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.