In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Ex Input:
What type of equipment is used with liquid oxygen but not other methods of oxygen storage?, Context: Oxygen storage methods include high pressure oxygen tanks, cryogenics and chemical compounds. For reasons of economy, oxygen is often transported in bulk as a liquid in specially insulated tankers, since one liter of liquefied oxygen is equivalent to 840 liters of gaseous oxygen at atmospheric pressure and 20 C (68 F). Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions with a need for large volumes of pure oxygen gas. Liquid oxygen is passed through heat exchangers, which convert the cryogenic liquid into gas before it enters the building. Oxygen is also stored and shipped in smaller cylinders containing the compressed gas; a form that is useful in certain portable medical applications and oxy-fuel welding and cutting.

Ex Output:
heat exchangers

Ex Input:
What gave these hunters their food supply?, Context: Evidence suggests big-game hunter gatherers crossed the Bering Strait from Asia (Eurasia) into North America over a land bridge (Beringia), that existed between 47,00014,000 years ago. Around 18,500-15,500 years ago, these hunter-gatherers are believed to have followed herds of now-extinct Pleistocene megafauna along ice-free corridors that stretched between the Laurentide and Cordilleran ice sheets. Another route proposed is that, either on foot or using primitive boats, they migrated down the Pacific coast to South America.

Ex Output:
big-game

Ex Input:
What legendary relic was said to be in the region of Avalon at one point?, Context: In Arthurian legend, Avalon became associated with Glastonbury Tor when monks at Glastonbury Abbey claimed to have discovered the bones of King Arthur and his queen. What is more certain is that Glastonbury was an important religious centre by 700 and claims to be "the oldest above-ground Christian church in the World" situated "in the mystical land of Avalon." The claim is based on dating the founding of the community of monks at AD 63, the year of the legendary visit of Joseph of Arimathea, who was supposed to have brought the Holy Grail. During the Middle Ages there were also important religious sites at Woodspring Priory and Muchelney Abbey. The present Diocese of Bath and Wells covers Somerset with the exception of the Parish of Abbots Leigh with Leigh Woods in North Somerset and a small area of Dorset. The Episcopal seat of the Bishop of Bath and Wells is now in the Cathedral Church of Saint Andrew in the city of Wells, having previously been at Bath Abbey. Before the English Reformation, it was a Roman Catholic diocese; the county now falls within the Roman Catholic Diocese of Clifton. The Benedictine monastery Saint Gregory's Abbey, commonly known as Downside Abbey, is at Stratton-on-the-Fosse, and the ruins of the former Cistercian Cleeve Abbey are near the village of Washford.

Ex Output:
Holy Grail