Dever was indicted for the murder of Vickers by poison. At trial, the prosecutor calls the county coroner, Dr. Wolfe, who is a boardcertified pathologist, to testify that, in accord with good practice in her specialty, she has studied microphotographic slides, made under her supervision by medical assistants, of tissue taken from Vickers' corpse and that it is Wolfe's opinion, based on that study, that Vickers died of poisoning. The slides have not been offered in evidence. Dr. Wolfe's opinion should be
excluded, because the cause of death is a critical issue to be decided by the trier of fact. 81  excluded, because her opinion is based on facts not in evidence.  admitted, because Wolfe followed accepted medical practice in arriving at her opinion  admitted, because her opinion is based on matters observed pursuant to a duty imposed by law.