A historian using a primary source to learn about U.S. president George Washington would most likely choose option B: reading a letter written by George Washington.
Primary sources are original, firsthand accounts or evidence from the time period being studied. They provide direct insights into historical events or individuals. In this case, a letter written by George Washington would be a primary source because it is an authentic document from his time as president.
By reading a letter written by George Washington, the historian can gain direct knowledge of his thoughts, actions, and perspectives. This allows for a deeper understanding of his presidency and the historical context in which he operated.
Options A, C, and D are not examples of using primary sources. A modern poem about George Washington would be a secondary source since it is not from his time period. Similarly, a biography about George Washington would also be a secondary source because it is based on other people's research and interpretation. Lastly, watching a play about George Washington would provide an interpretation or dramatization of events, but it would not offer direct insights into his presidency.
In summary, to learn about U.S. president George Washington, a historian would best utilize a primary source such as a letter written by George Washington.