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: Radiology
True about OCG is – a) First done by Graham Cole in 1942b) Dye ingested at rate of 1 ml/kgc) USG has replaced itd) Dye used is telepaque 
Select and explain. 
A. ab, B. cd, C. bd, D. ac
B: cd
Answer: B: cd 
Explanation: OCG was introduced by Graham and Cole in 1924 (not in 1942).
Two doses of 3 gm of dye is given --> first dose 14 hours, and second dose 3-4 hours prior to post-contrast examination.
OCG has largely been replaced by USG
Dye most commonly used is Na/Ca Ipanoic acid (Telepaque).