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The pigment that causes urine to be yellow in color is urochrome. Urochrome is a pigment produced from the breakdown of hemoglobin in the liver and is responsible for the typical yellow hue seen in urine. It results from the degradation of heme, specifically from the conversion of biliverdin into bilirubin and then to urochrome, which is excreted in urine.

Other pigments listed, such as dichromate, porphyrins, and urochromate, do not contribute to the color of urine in the same way. Dichromate is a chemical compound often used in laboratory settings and has no physiological role in urine coloration. Porphyrins are involved in various biochemical processes and are associated with certain disorders but are not responsible for the yellow color of normal urine. Urochromate seems similar in name to urochrome, but it is not a recognized pigment related to urine color and is less relevant as a contributor compared to the well-documented urochrome. Thus, urochrome is the primary pigment responsible for the characteristic yellow color of urine.