Q: Question: "What prevents building a mass transit system underground in Miami?" Context: "Beneath the plain lies the Biscayne Aquifer, a natural underground source of fresh water that extends from southern Palm Beach County to Florida Bay, with its highest point peaking around the cities of Miami Springs and Hialeah. Most of the Miami metropolitan area obtains its drinking water from this aquifer. As a result of the aquifer, it is not possible to dig more than 15 to 20 ft (5 to 6 m) beneath the city without hitting water, which impedes underground construction, though some underground parking garages exist. For this reason, the mass transit systems in and around Miami are elevated or at-grade.[citation needed]" Answer:
A: Biscayne Aquifer

Q: Question: "what is the second type of energy source mentioned?" Context: "In 2004, a large share of natural gas reserves in Iran were untapped. The addition of new hydroelectric stations and the streamlining of conventional coal and oil-fired stations increased installed capacity to 33,000 megawatts. Of that amount, about 75% was based on natural gas, 18% on oil, and 7% on hydroelectric power. In 2004, Iran opened its first wind-powered and geothermal plants, and the first solar thermal plant is to come online in 2009. Iran is the third country in the world to have developed GTL technology." Answer:
A: hydroelectric

Q: Question: "What does Zen place primary importance on?" Context: "Zen Buddhism (), pronounced Chan in Chinese, seon in Korean or zen in Japanese (derived from the Sanskrit term dhyana, meaning "meditation") is a form of Buddhism that became popular in China, Korea and Japan and that lays special emphasis on meditation.[note 12] Zen places less emphasis on scriptures than some other forms of Buddhism and prefers to focus on direct spiritual breakthroughs to truth." Answer:
A: direct spiritual breakthroughs to truth

Q: Question: "What intangible object is central to the proper functioning of a lighting fixture?" Context: "Lighting fixtures come in a wide variety of styles for various functions. The most important functions are as a holder for the light source, to provide directed light and to avoid visual glare. Some are very plain and functional, while some are pieces of art in themselves. Nearly any material can be used, so long as it can tolerate the excess heat and is in keeping with safety codes." Answer:
A:
safety codes