Final answer:
Blood urea nitrogen (BUN) is the test used to assess liver function, particularly nitrogen metabolism, because urea is synthesized in the liver and serves as a marker of liver activity.Thus the bcorrect option is c.
Step-by-step explanation:
For the assessment of liver function, specifically nitrogen metabolism, blood urea nitrogen (BUN) is tested. Urea is synthesized in the liver from ammonia that is released by the oxidation of amino acids. It serves as a non-toxic, water-soluble vehicle for excreting ammonia. Normally, blood urea is maintained at a concentration of 15-40 mg/100 ml. Elevated BUN levels can be an indicator of liver dysfunction, as the liver is responsible for urea synthesis. However, it is important to note that BUN is also an indicator of kidney function, as urea is excreted through the kidneys.