[Solved] In a single-subject phase change design,when does a researcher change phases? A)after 3 observations B)after 5 or 6 observations C)when the data show a clear and stable pattern D)at the beginning of each week Courtesans: Courtesans were historically educated and sophisticated women who served as companions and sometimes sexual partners to wealthy or powerful men. Hetaerae: In ancient Greece, educated and sophisticated companions or courtesans who engaged in long-term relationships with powerful men for their mutual benefit. Ancient Greece: A period and place in history noted for its significant contributions to art, philosophy, politics, and the early development of democracy. Erotic Wall Murals: Artworks painted on walls that depict sexually explicit scenes or themes.