Ans: d (Flip chart) Ref: Park, 19h ed, p. 717Flip chart- They consist of a series of charts, each with an illustration pertaining to the talk to be given. They are meant to be shown one after another. The message on the chart must be brief and to the point.Flannel graph- A piece of rough flannel or khadi fixed over a wooden board provides a background for displaying cut out postures, graphs and other illustrations.Exhibits- Objects, models, specimen, etc convey a specific message to the viewer.