Final answer:
The St. George's Cross would have likely been the flag raised for the play The Tempest, signifying its classical themes and relation to English identity.
Step-by-step explanation:
The flag that would have been raised for the play The Tempest is likely the St. George's Cross. Historical records of theater practices during the time when Shakespeare's plays were originally performed indicate that different flags were used to signify the genre of the play being performed that day. The St. George's Cross, a red cross on a white background, was typically used to signify a history play or a play based on English themes. The Tempest, while a work of fiction, features classical themes and elements that are closely tied to English identity, similar to the way historical plays would have been. Therefore, this flag would be more appropriate than the other options listed, such as the Union Jack, which represents the union of different countries under one sovereign, the White Ensign, which is specifically associated with the Royal Navy, or the Jolly Roger, which is associated with piracy and would not have been relevant to this play.