<prompt> Which of the following statements about contrast in radiography is true -Ionic monomers have three iodine atoms per two paicles in solutionHigh osmolar contrast agents may be ionic or non ionicGadolinum may cross the blood brain barrierIohexol is a high osmolar contrast media  <response>: option A is correct : Ionic monomers have three iodine atoms per two paicles in solution Ionic dimers and non ionic monomers have three iodine atoms per one paicle in solution Non ionic dimers have six iodine atoms per one paicle in solution option B is incorrect : High osmolar agents ionic monomers are only ionic low osmolar agents may be ionic or non ionic iso osmolar agents are only non ionic option C is incorrect : Gadolinium does not cross Blood brain barrier BBB option D is incorrect : Iohexol is low osmolar non ionic monomer 