This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

General Dong Zhuo (d. 192 AD) found the young emperor and his brother wandering in the countryside. He escorted them safely back to the capital and was made Minister of Works, taking control of Luoyang and forcing Yuan Shao to flee. After Dong Zhuo demoted Emperor Shao and promoted his brother Liu Xie as Emperor Xian, Yuan Shao led a coalition of former officials and officers against Dong, who burned Luoyang to the ground and resettled the court at Chang'an in May 191 AD. Dong Zhuo later poisoned Emperor Shao.
How was Luoyang destroyed?

48 of Switzerland's mountains are 4,000 metres (13,000 ft) above sea in altitude or higher. At 4,634 m (15,203 ft), Monte Rosa is the highest, although the Matterhorn (4,478 m or 14,692 ft) is often regarded as the most famous. Both are located within the Pennine Alps in the canton of Valais. The section of the Bernese Alps above the deep glacial Lauterbrunnen valley, containing 72 waterfalls, is well known for the Jungfrau (4,158 m or 13,642 ft) Eiger and Mönch, and the many picturesque valleys in the region. In the southeast the long Engadin Valley, encompassing the St. Moritz area in canton of Graubünden, is also well known; the highest peak in the neighbouring Bernina Alps is Piz Bernina (4,049 m or 13,284 ft).
What is the highest mountain in Switzerland?

For any animal, survival requires maintaining a variety of parameters of bodily state within a limited range of variation: these include temperature, water content, salt concentration in the bloodstream, blood glucose levels, blood oxygen level, and others. The ability of an animal to regulate the internal environment of its body—the milieu intérieur, as pioneering physiologist Claude Bernard called it—is known as homeostasis (Greek for "standing still"). Maintaining homeostasis is a crucial function of the brain. The basic principle that underlies homeostasis is negative feedback: any time a parameter diverges from its set-point, sensors generate an error signal that evokes a response that causes the parameter to shift back toward its optimum value. (This principle is widely used in engineering, for example in the control of temperature using a thermostat.)

Homeostasis is defined as what?