Bilirubin is absent in urine because it is -: (A) Distributed in the body fat, (B) Conjugated with glucoronide, (C) Not filterable, (D) Lipophilic
Answer is D. Unconjugated bilirubin cannot be excreted in urine because:-

(i) It is lipophilic (lipid soluble) but not water soluble, i.e. it is hydrophobic 
(ii) It is tightly bound to albumin, thus cannot be filtered at glomeruli.