Answer : 4. "Urochrome"
Explanation :

The yellow color of human urine is primarily due to a pigment called urochrome. Urochrome is a waste product resulting from the breakdown of hemoglobin, a protein in red blood cells. The varying shades of yellow in urine can be influenced by factors such as hydration levels, diet, and certain medications, but urochrome is the main pigment responsible for the typical yellow color of urine.