In this conversation, which group discussion technique does emily most clearly show? emily: wait, wait, that totally destroys the book's credibility! if medieval masterpieces [by francis eggbert] is fiction, and pettit is using it as a source, then that means pettit's assumptions are probably inaccurate. han: got that right. and eggbert is a famous historian. he's even got a show on the radio. a. challenging the credibility of sources b. conducting extra research c. asking clarifying questions d. determining new research goals