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: Matisse was also one of the first 20th-century artists to make color the central element of the painting, chosen to evoke emotions. "A certain blue penetrates your soul", he wrote. "A certain red affects your blood pressure." He also was familiar with the way that complementary colors, such as red and green, strengthened each other when they were placed next to each other. He wrote, "My choice of colors is not based on scientific theory; it is based on observation, upon feelings, upon the real nature of each experience ... I just try to find a color which corresponds to my feelings." Question: What color did Matisse say could penetate ones soul?
Example Output: blue

Example Input: Passage: The U.S. Navy, by contrast, relied on commerce raiding from the outset. However, the problem of Allied forces surrounded in the Philippines, during the early part of 1942, led to diversion of boats to "guerrilla submarine" missions. As well, basing in Australia placed boats under Japanese aerial threat while en route to patrol areas, reducing their effectiveness, and Nimitz relied on submarines for close surveillance of enemy bases. Furthermore, the standard-issue Mark 14 torpedo and its Mark VI exploder both proved defective, problems which were not corrected until September 1943. Worst of all, before the war, an uninformed US Customs officer had seized a copy of the Japanese merchant marine code (called the "maru code" in the USN), not knowing that the Office of Naval Intelligence (ONI) had broken it. The Japanese promptly changed it, and the new code was not broken again by OP-20G until 1943. Question: What was the "maru code"?
Example Output: Japanese merchant marine code

Example Input: Passage: As a young child, Bell, like his brothers, received his early schooling at home from his father. At an early age, however, he was enrolled at the Royal High School, Edinburgh, Scotland, which he left at age 15, completing only the first four forms. His school record was undistinguished, marked by absenteeism and lacklustre grades. His main interest remained in the sciences, especially biology, while he treated other school subjects with indifference, to the dismay of his demanding father. Upon leaving school, Bell travelled to London to live with his grandfather, Alexander Bell. During the year he spent with his grandfather, a love of learning was born, with long hours spent in serious discussion and study. The elder Bell took great efforts to have his young pupil learn to speak clearly and with conviction, the attributes that his pupil would need to become a teacher himself. At age 16, Bell secured a position as a "pupil-teacher" of elocution and music, in Weston House Academy, at Elgin, Moray, Scotland. Although he was enrolled as a student in Latin and Greek, he instructed classes himself in return for board and 10 per session. The following year, he attended the University of Edinburgh; joining his older brother Melville who had enrolled there the previous year. In 1868, not long before he departed for Canada with his family, Bell completed his matriculation exams and was accepted for admission to the University of London. Question: How old was Bell when he became a "pupil-teacher"?
Example Output:
16