TASK DEFINITION: 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.
PROBLEM: Passage: During the administration of U.S. President Martin Van Buren, nearly 17,000 Cherokees—along with approximately 2,000 black slaves owned by Cherokees—were uprooted from their homes between 1838 and 1839 and were forced by the U.S. military to march from "emigration depots" in Eastern Tennessee (such as Fort Cass) toward the more distant Indian Territory west of Arkansas. During this relocation an estimated 4,000 Cherokees died along the way west. In the Cherokee language, the event is called Nunna daul Isunyi—"the Trail Where We Cried." The Cherokees were not the only American Indians forced to emigrate as a result of the Indian removal efforts of the United States, and so the phrase "Trail of Tears" is sometimes used to refer to similar events endured by other American Indian peoples, especially among the "Five Civilized Tribes". The phrase originated as a description of the earlier emigration of the Choctaw nation. Question: How many Cherokee-owned black slaves were also relocated between 1838 and 1839?

SOLUTION: 2,000

PROBLEM: Passage: Cultural and career issues in the U.S. Air Force have been cited as one of the reasons for the shortfall in needed UAV operators. In spite of an urgent need for UAVs or drones to provide round the clock coverage for American troops during the Iraq War, the USAF did not establish a new career field for piloting them until the last year of that war and in 2014 changed its RPA training syllabus again, in the face of large aircraft losses in training, and in response to a GAO report critical of handling of drone programs. Paul Scharre has reported that the cultural divide between the USAF and US Army has kept both services from adopting each other's drone handing innovations. Question: What is the reason for the shortage of UAV operators in the US Air Force?

SOLUTION: Cultural and career issues

PROBLEM: Passage: Valencia stands on the banks of the Turia River, located on the eastern coast of the Iberian Peninsula and the western part of the Mediterranean Sea, fronting the Gulf of Valencia. At its founding by the Romans, it stood on a river island in the Turia, 6.4 km (4 mi) from the sea. The Albufera, a freshwater lagoon and estuary about 11 km (7 mi) south of the city, is one of the largest lakes in Spain. The City Council bought the lake from the Crown of Spain for 1,072,980 pesetas in 1911, and today it forms the main portion of the Parc Natural de l'Albufera (Albufera Nature Reserve), with a surface area of 21,120 hectares (52,200 acres). In 1986, because of its cultural, historical, and ecological value, the Generalitat Valenciana declared it a natural park. Question: How far from the sea was Valencia when it was founded?

SOLUTION:
6.4 km