instruction:
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.
question:
Passage: Between 2000 and 2004 an average of 478 crimes were reported each day in Mexico City; however, the actual crime rate is thought to be much higher "since most people are reluctant to report crime". Under policies enacted by Mayor Marcelo Ebrard between 2009 and 2011, Mexico City underwent a major security upgrade with violent and petty crime rates both falling significantly despite the rise in violent crime in other parts of the country. Some of the policies enacted included the installation of 11,000 security cameras around the city and a very large expansion of the police force. Mexico City has one of the world's highest police officer-to-resident ratios, with one uniformed officer per 100 citizens. Question: What Mexican mayor tried to crack down on crime immensely? 
answer:
Marcelo Ebrard


question:
Passage: French historians traditionally place the Enlightenment between 1715, the year that Louis XIV died, and 1789, the beginning of the French Revolution. Some recent historians begin the period in the 1620s, with the start of the scientific revolution. The Philosophes, the French term for the philosophers of the period, widely circulated their ideas through meetings at scientific academies, Masonic lodges, literary salons and coffee houses, and through printed books and pamphlets. The ideas of the Enlightenment undermined the authority of the monarchy and the church, and paved the way for the revolutions of the 18th and 19th centuries. A variety of 19th-century movements, including liberalism and neo-classicism, trace their intellectual heritage back to the Enlightenment. Question: What year did the Enlightenment begin according to French historians?
answer:
1715


question:
Passage: The climatic changes of the late Jurassic and Cretaceous provided for further adaptive radiation. The Jurassic was the height of archosaur diversity, and the first birds and eutherian mammals also appeared. Angiosperms radiated sometime in the early Cretaceous, first in the tropics, but the even temperature gradient allowed them to spread toward the poles throughout the period. By the end of the Cretaceous, angiosperms dominated tree floras in many areas, although some evidence suggests that biomass was still dominated by cycad and ferns until after the Cretaceous–Paleogene extinction. Question: What types of species are thought to still have been dominate until after the extinction?
answer:

cycad and ferns