Instructions: 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.
Input: Passage: In Virginia prior to 1920, for example, a person was legally white if having seven-eights or more white ancestry. The one-drop rule originated in some Southern United States in the late 19th century, likely in response to whites' attempt to maintain white supremacy and limit black political power following the Democrats' regaining control of state legislatures in the late 1870s. The first year in which the U.S. Census dropped the mulatto category was 1920; that year enumerators were instructed to classify people in a binary way as white or black. This was a result of the Southern-dominated Congress convincing the Census Bureau to change its rules.
Output:
When was a person legally white in South Carolina before 1920?