instruction:
In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
question:
Question: How high is the gamma radiation from nuclear fuel? Passage:The nuclear fuel elements were made of refractory ceramic based on beryllium oxide, with enriched uranium dioxide as fuel and small amount of zirconium dioxide for structural stability. The fuel elements were hollow hexagonal tubes about long with distance between the outer parallel planes, with inside diameter of . They were manufactured by high-pressure extruding of the green compact, then sintering almost to its theoretical density. The core consisted of 465,000 individual elements stacked to form 27,000 airflow channels; the design with small unattached elements reduced problems related with thermal stresses. The elements were designed for average operation temperature of ; the autoignition temperature of the reactor base plates was only 150 °C higher. The neutron flux was calculated to be 9×10 neutrons/(cm·s) in the aft and 7×10 neutrons/(cm·s) in the nose. The gamma radiation level was fairly high due to the lack of shielding; radiation hardening for the guidance electronics had to be designed.
 Links: a. Beryllium oxide b. Radiation hardening c. Nuclear fuel d. Radiation hardening
answer:
c


question:
Question: What age bracket plays for the Real Madrid's youth system? Passage:Casillas began his career in Real Madrid's youth system, known as La Fábrica, during the 1990–91 season. On 27 November 1997, at age 16 and still a junior, he was first called up to the senior team squad to face Rosenborg in the UEFA Champions League, although he remained on the bench throughout. After spending a season with the C-team in the fourth tier, during which they won their regional group, he came into contention as the club's first-choice between the posts. In starting the 1999–2000 UEFA Champions League group stage fixture against Olympiakos on 15 September 1999, he became the youngest goalkeeper ever to feature in the competition at the time, aged 18 years and 177 days; a record which was only broken in October 2017 by Mile Svilar. Three days earlier, Casillas had made his La Liga debut in a 2–2 draw against Athletic Bilbao at San Mamés Stadium. In May 2000, he became the youngest ever goalkeeper to play in and win a Champions League final when Real Madrid defeated Valencia 3–0, just four days after his 19th birthday.
 Links: a. Olympiacos F.C. b. Real Madrid CF (youth) c. La Fábrica d. Real Madrid CF (youth)
answer:
b


question:
Question: Did the highest scoring fighter ace have any siblings? Passage:After a short rest, the 90th continued across the Moselle River to take Mainz, 22 March, and crossed the rivers Rhine, the Main, and the Werra in rapid succession. Pursuit continued to the Czech border, 18 April 1945, and into the Sudetes mountain range. The division was en route to Prague when they came upon the remaining 1500 emaciated prisoners left behind by the SS at Flossenbürg concentration camp. Today, a memorial wall at the former camp honors the 90th as the liberators of Flossenbürg concentration camp. A week later, word came that the war in Europe ended on 8 May 1945. On that same day, Erich Hartmann, the highest-scoring fighter ace in history, along with a squadron of the elite Jagdgeschwader 52 fighter wing (the highest-scoring fighter wing in history), surrendered to the 90th.
 Links: a. Main (river) b. Jagdgeschwader 52 c. Prague d. Erich Hartmann
answer:

d