This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

Example Input: Passage: In the mid-1950s, Frank Burnet, inspired by a suggestion made by Niels Jerne, formulated the clonal selection theory (CST) of immunity. On the basis of CST, Burnet developed a theory of how an immune response is triggered according to the self/nonself distinction: "self" constituents (constituents of the body) do not trigger destructive immune responses, while "nonself" entities (e.g., pathogens, an allograft) trigger a destructive immune response. The theory was later modified to reflect new discoveries regarding histocompatibility or the complex "two-signal" activation of T cells. The self/nonself theory of immunity and the self/nonself vocabulary have been criticized, but remain very influential. Question: What property of T cells caused modification of CST?
Example Output: the complex "two-signal" activation

Example Input: Passage: Efforts to identify the origins of Ashkenazi Jews through DNA analysis began in the 1990s. Currently, there are three types of genetic origin testing, autosomal DNA (atDNA), mitochondrial DNA (mtDNA), and Y-chromosomal DNA (Y-DNA). Autosomal DNA is a mixture from an individual's entire ancestry, Y-DNA shows a male's lineage only along his strict-paternal line, mtDNA shows any person's lineage only along the strict-maternal line. Genome-wide association studies have also been employed to yield findings relevant to genetic origins. Question: How many types of genetic origin testing currently exist?
Example Output: three types of genetic origin testing

Example Input: Passage: By 1990, the Census Bureau included more than a dozen ethnic/racial categories on the census, reflecting not only changing social ideas about ethnicity, but the wide variety of immigrants who had come to reside in the United States due to changing historical forces and new immigration laws in the 1960s. With a changing society, more citizens have begun to press for acknowledging multiracial ancestry. The Census Bureau changed its data collection by allowing people to self-identify as more than one ethnicity. Some ethnic groups are concerned about the potential political and economic effects, as federal assistance to historically underserved groups has depended on Census data. According to the Census Bureau, as of 2002, over 75% of all African Americans had multiracial ancestries. Question: How many African Americans identify as multiracial on the Census of 2002?
Example Output:
over 75%