Answer:
a. Water, urea, mineral salts and pigments
Explanation:
The composition of urea of a normal healthy human consist of Water, urea, mineral salts and pigments. The water which is present in excess amount in our body will be removed by the body. Our body need salts in low amount which is taken from the food while the excess amount of salts and some pigments in the foods are also removed through the process of excretion and added into the urine. Due to these pigments, the color of urine is yellowish.