Problem: The period saw several important technical innovations, like the principle of linear perspective found in the work of Masaccio, and later described by Brunelleschi. Greater realism was also achieved through the scientific study of anatomy, championed by artists like Donatello. This can be seen particularly well in his sculptures, inspired by the study of classical models. As the centre of the movement shifted to Rome, the period culminated in the High Renaissance masters da Vinci, Michelangelo and Raphael.
Along with da Vinci, who were two other artists regarded as masters of the High Renaissance?
The answer is the following: Michelangelo and Raphael

Problem: The Houston area is a leading center for building oilfield equipment. Much of its success as a petrochemical complex is due to its busy ship channel, the Port of Houston. In the United States, the port ranks first in international commerce and tenth among the largest ports in the world. Unlike most places, high oil and gasoline prices are beneficial for Houston's economy, as many of its residents are employed in the energy industry. Houston is the beginning or end point of numerous oil, gas, and products pipelines:
What has the Houston ship channel served to promote into success?
The answer is the following: petrochemical complex

Problem: Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic, such as Banks Island, and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much water vapor. Even during glacial periods of the Quaternary, Manchuria, lowland Siberia, and central and northern Alaska, though extraordinarily cold, had such light snowfall that glaciers could not form.
Why can't glaciers form in polar deserts?
The answer is the following: they receive little snowfall

Problem: St. Barthélemy has about 25 hotels, most of them with 15 rooms or fewer. The largest has 58 rooms. Hotels are classified in the traditional French manner; 3 Star, 4 Star and 4 Star Luxe. Of particular note are Eden Rock and Cheval Blanc. Hotel Le Toiny, the most expensive hotel on the island, has 12 rooms. Most places of accommodation are in the form of private villas, of which there are some 400 available to rent on the island. The island's tourism industry, though expensive, attracts 70,000 visitors every year to its luxury hotels and villas and another 130,000 people arrive by luxury boats. It also attracts a labour force from Brazil and Portugal to meet the industry needs.
About how many villas are available for rent in St. Barts?
The answer is the following:
400