TASK DEFINITION: This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
PROBLEM: Passage: Machine vision systems often require bright and homogeneous illumination, so features of interest are easier to process. LEDs are often used for this purpose, and this is likely to remain one of their major uses until the price drops low enough to make signaling and illumination uses more widespread. Barcode scanners are the most common example of machine vision, and many low cost products use red LEDs instead of lasers. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons:

SOLUTION:  non-LEDs are often used for what type of systems?

PROBLEM: Passage: West of the Rocky Mountains lies the Intermontane Plateaus (also known as the Intermountain West), a large, arid desert lying between the Rockies and the Cascades and Sierra Nevada ranges. The large southern portion, known as the Great Basin, consists of salt flats, drainage basins, and many small north-south mountain ranges. The Southwest is predominantly a low-lying desert region. A portion known as the Colorado Plateau, centered around the Four Corners region, is considered to have some of the most spectacular scenery in the world. It is accentuated in such national parks as Grand Canyon, Arches, Mesa Verde National Park and Bryce Canyon, among others. Other smaller Intermontane areas include the Columbia Plateau covering eastern Washington, western Idaho and northeast Oregon and the Snake River Plain in Southern Idaho.

SOLUTION: What is the name of the plateau that lies east of the Rocky Mountains?

PROBLEM: Passage: After the Xinhai Revolution (1911–12) toppled the Qing dynasty and the last Qing troops were escorted out of Tibet, the new Republic of China apologized for the actions of the Qing and offered to restore the Dalai Lama's title. The Dalai Lama refused any Chinese title and declared himself ruler of an independent Tibet. In 1913, Tibet and Mongolia concluded a treaty of mutual recognition. For the next 36 years, the 13th Dalai Lama and the regents who succeeded him governed Tibet. During this time, Tibet fought Chinese warlords for control of the ethnically Tibetan areas in Xikang and Qinghai (parts of Kham and Amdo) along the upper reaches of the Yangtze River. In 1914 the Tibetan government signed the Simla Accord with Britain, ceding the South Tibet region to British India. The Chinese government denounced the agreement as illegal.

SOLUTION:
What revolution took place in 1913?