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.

[Q]: Passage: The fourth Yuan emperor, Buyantu Khan (Ayurbarwada), was a competent emperor. He was the first Yuan emperor to actively support and adopt mainstream Chinese culture after the reign of Kublai, to the discontent of some Mongol elite. He had been mentored by Li Meng, a Confucian academic. He made many reforms, including the liquidation of the Department of State Affairs (Chinese: 尚書省), which resulted in the execution of five of the highest-ranking officials. Starting in 1313 the traditional imperial examinations were reintroduced for prospective officials, testing their knowledge on significant historical works. Also, he codified much of the law, as well as publishing or translating a number of Chinese books and works.
[A]:  Who was the 3rd to rule the Yuan dynasty?


[Q]: Passage: The noise-based speed is defined as the exposure that will lead to a given signal-to-noise ratio on individual pixels. Two ratios are used, the 40:1 ("excellent image quality") and the 10:1 ("acceptable image quality") ratio. These ratios have been subjectively determined based on a resolution of 70 pixels per cm (178 DPI) when viewed at 25 cm (9.8 inch) distance. The signal-to-noise ratio is defined as the standard deviation of a weighted average of the luminance and color of individual pixels. The noise-based speed is mostly determined by the properties of the sensor and somewhat affected by the noise in the electronic gain and AD converter.
[A]: Which ratio was subjectively determined?


[Q]: Passage: The Warnerke Standard Sensitometer consisted of a frame holding an opaque screen with an array of typically 25 numbered, gradually pigmented squares brought into contact with the photographic plate during a timed test exposure under a phosphorescent tablet excited before by the light of a burning Magnesium ribbon. The speed of the emulsion was then expressed in 'degrees' Warnerke (sometimes seen as Warn. or °W.) corresponding with the last number visible on the exposed plate after development and fixation. Each number represented an increase of 1/3 in speed, typical plate speeds were between 10° and 25° Warnerke at the time.
[A]:
The Warnerke Standard Sensitometer has 25 opaque what?