Final answer:
The flashback of an artist in Mr. Peabody's memory could involve prominent figures like Amy Sherald or Benjamin West, who have made significant contributions to art history and culture.
Step-by-step explanation:
When Mr. Peabody has a flashback of an artist, it is most likely referring to a moment related to famous artists such as Amy Sherald, known for her distinct portraits of African Americans or Benjamin West, celebrated for historic paintings like 'Benjamin Franklin Drawing Electricity from the Sky.' Alternatively, it could reference various artists who influenced popular culture at different times, including illustrators like John R. Chapin or earlier figures like the Beardsley Limner. These artist flashbacks are typically used to provide historical context or to showcase the significant role that artists have played in documenting and shaping our perception of people and events throughout history.