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: The Yuan dynasty is considered both a successor to the Mongol Empire and an imperial Chinese dynasty. It was the khanate ruled by the successors of Möngke Khan after the division of the Mongol Empire. In official Chinese histories, the Yuan dynasty bore the Mandate of Heaven, following the Song dynasty and preceding the Ming dynasty. The dynasty was established by Kublai Khan, yet he placed his grandfather Genghis Khan on the imperial records as the official founder of the dynasty as Taizu.[b] In the Proclamation of the Dynastic Name (《建國號詔》), Kublai announced the name of the new dynasty as Great Yuan and claimed the succession of former Chinese dynasties from the Three Sovereigns and Five Emperors to the Tang dynasty. Question: Who was Kublai Khan's grandfather?

SOLUTION: Genghis Khan

PROBLEM: Passage: Droney's health was poor and Kerry had decided to run for his position in the 1978 election should Droney drop out. However, Droney was re-elected and his health improved; he went on to re-assume many of the duties that he had delegated to Kerry. Kerry thus decided to leave, departing in 1979 with assistant DA Roanne Sragow to set up their own law firm. Kerry also worked as a commentator for WCVB-TV and co-founded a bakery, Kilvert & Forbes Ltd., with businessman and former Kennedy aide K. Dun Gifford. Question: Who left the DA's office with Kerry?

SOLUTION: Roanne Sragow

PROBLEM: Passage: The Gregorian calendar improves the approximation made by the Julian calendar by skipping three Julian leap days in every 400 years, giving an average year of 365.2425 mean solar days long. This approximation has an error of about one day per 3,300 years with respect to the mean tropical year. However, because of the precession of the equinoxes, the error with respect to the vernal equinox (which occurs, on average, 365.24237 days apart near 2000) is 1 day every 7,700 years, assuming a constant time interval between vernal equinoxes, which is not true. By any criterion, the Gregorian calendar is substantially more accurate than the 1 day in 128 years error of the Julian calendar (average year 365.25 days). Question: How many days must be skipped to align the calendar with mean solar days in a year?

SOLUTION:
three Julian leap days