The correct option is (c) urea.
Explanation:
In ornithine cycle urea (H2N -Co -NH2) is formed from two molecules of ammonia and one molecule of CO2 .A molecule of ammonia combines with CO2 in mitochondrion to form carbamoyl phosphate. In the cytoplasm it reacts with ornithine producing citrulline. Citrulline accepts another molecule of NH4+ giving rise to arginine. Arginine is hydrolysed into urea and ornithine with the help of enzyme arginase.
