Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: The 10th Cavalry returned from the Philippines in late 1902 and settled down in different posts in the south western United States. Patrols and garrison life was the routine for the regiment. Under war plans, the 10th was designated for service in the Pacific and support in the Philippines from 1915 through 1942 but never rotated there. The 9th Cavalry Regiment became "Park Rangers" in 1905 for Yosemite National Park and other state and federal lands. The Troopers' Campaign Hat, sporting the "Montana Pinch" used to help shed the tropical downpours. That "Montana Pinch" gave the hat the distinctive look we recognize today as the "Smokey Bear Hat". 
 Question: Which cavalry is credited with the Smokey Bear Hat, 10th or 9th?
Example Output: 9th cavalry regiment

Example Input: Context: Biologists agree that the ancestor of mitochondria was an alpha-proteobacterium. But there is no consensus as to what constitutes an alpha-proteobacterial gene. Is it a gene found in all or several alpha-proteobacteria, or in only one? Here, we examine the proportion of alpha-proteobacterial genes in alpha-proteobacterial genomes by means of sequence comparisons. We find that each alpha-proteobacterium harbours a particular collection of genes and that, depending upon the lineage examined, between 97 and 33% are alpha-proteobacterial by the nearest-neighbour criterion. Our findings bear upon attempts to reconstruct the mitochondrial ancestor and upon inferences concerning the collection of genes that the mitochondrial ancestor possessed at the time that it became an endosymbiont. 
 Question: Which species of bacteria did the mitochondria originate from?
Example Output: biologists agree that the ancestor of mitochondria was an alpha-proteobacterium.

Example Input: Context: For travellers who want to experience some of the history and mystery of the ancient world, here is a list of cool destinations for your next holiday. Angkor Wat, Cambodia Built in the 12th century, Angkor Wat (meaning "capital monastery") was a temple in the ancient Khmer capital city of Angkor. It is Cambodia's best-known tourist attraction and is famed for its beautiful architecture and reliefs. You'll need at least three days to fully discover the delights of this magnificent site. Machu Picchu, Peru Machu Picchu was built high in the Andes Mountains of South America by the Inca in the 15th century. Although well preserved its exact purpose is unknown. It is famous throughout the world not only for its incredible design but also for the natural beauty that surrounds it. Give yourself a week to explore this magnificent site. Stonehenge, England The entire Stonehenge site was constructed over thousands of years. But why and how it was built remains a mystery. As the weather can be pretty bleak in winter and the crowds huge in summer, we suggest autumn should be the best time to visit these monster rocks. Pompeii, Italy When Mount Vesuvius erupted in 79 A.D., Pompeii was buried under many layers of ash, preserving the city exactly as it was when the volcano erupted. Because so many objects were preserved, scientists and visitors are able to better understand daily life in the ancient Roman Empire. 
 Question: Which location offers the most direct view into daily life in the ancient world?
Example Output:
pompeii.