Abyproduct of amino acid catabolism in the liver is

B. Urea

Explanation:

Urea is a byproduct of amino acid catabolism in the liver.Excess amino acids undergoes the process of deamination in the liver. During the process of deamination, the amino acids are broken down into amine group and a carboxyl group.The amine group is then reduced to ammonia by addition of a hydrogen atom while the carboxyl group or the non-nitrogenous part is converted to fats or carbohydrates. Ammonia is then removed from the body in form of urea.