This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
Benzidine test detects -a) Hemoglobinb) Myoglobinc) Porphobilinogend) Bilirubine) Biliverdin 
Select and explain. 
A. ac, B. a, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: Benzidine test is based on the peroxidase activity of haematin, derived from oxidation of hair of haemoglobin (and methemoglobin). This enzyme, in the presence of H2O2 converts colourless salts into coloured bases.