Which organ serves as the primary site of amino acid metabolism (i. e. oxidation, transamination, deamination, gluconeogenesis, etc.)?

The liver

Explanation:

The liver -

In human beings the location of liver is just in the upper right portion of the abdomen , exactly below the diaphragm .

Liver is present in specifically vertebrates , and is responsible for various metabolism , like producing hormones , decomposition of the red blood cells , regulating the storage of glycogen and the synthesis of proteins .

Liver is the main site for the process of gluconeogenesis , amino acid catabolism .

Liver is the very organ , that has full urea cycle .

Hence , from the given information of the question ,

The correct term is the liver .