This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: In the late 19th century, three European-American middle-class female teachers married Indigenous American men they had met at Hampton Institute during the years when it ran its Indian program. In the late nineteenth century, Charles Eastman, a physician of European and Sioux ancestry who trained at Boston University, married Elaine Goodale, a European-American woman from New England. They met and worked together in Dakota Territory when she was Superintendent of Indian Education and he was a doctor for the reservations. His maternal grandfather was Seth Eastman, an artist and Army officer from New England, who had married a Sioux woman and had a daughter with her while stationed at Fort Snelling in Minnesota.
How many African-American teachers married Indigenous American men they had met at Hampton Institute?