liam's group is trying to come up with ideas for their group project, so each group member creates a list of ideas and notes why each idea has merit. group members read one another's lists, offering comments about the strengths and weaknesses of each idea. once liam gets his list back with the others' comments, he writes his own reactions to those comments, and then the list goes back into the pile so the group can finally make a master list of ideas worthy of additional discussion. liam's group is using what method of idea generation?