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.

Example Input: In 1872, Russian Alexander Lodygin invented an incandescent light bulb and obtained a Russian patent in 1874. He used as a burner two carbon rods of diminished section in a glass receiver, hermetically sealed, and filled with nitrogen, electrically arranged so that the current could be passed to the second carbon when the first had been consumed. Later he lived in the USA, changed his name to Alexander de Lodyguine and applied and obtained patents for incandescent lamps having chromium, iridium, rhodium, ruthenium, osmium, molybdenum and tungsten filaments, and a bulb using a molybdenum filament was demonstrated at the world fair of 1900 in Paris.
Example Output: Who patented an incandescent light bulb in Russia in 1874?

Example Input: In December 1993, the Famicom received a similar redesign. It also loads cartridges through a covered slot on the top of the unit and uses non-hardwired controllers. Because HVC-101 used composite video output instead of being RF only like the HVC-001, Nintendo marketed the newer model as the AV Famicom (AV, Eibui Shiyo Famikon?). Since the new controllers don't have microphones on them like the second controller on the original console, certain games such as the Disk System version of The Legend of Zelda and Raid on Bungeling Bay will have certain tricks that cannot be replicated when played on an HVC-101 Famicom without a modded controller. However, the HVC-101 Famicom is compatible with most NES controllers due to having the same controller port. Nintendo had also released a 3D graphic capable headset. However, this peripheral was never released outside Japan.[citation needed]
Example Output: What month and year did the Famicom receive a redesign?

Example Input: The simplest method, used for small-scale production and often by hobbyists, is immersion etching, in which the board is submerged in etching solution such as ferric chloride. Compared with methods used for mass production, the etching time is long. Heat and agitation can be applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to splash boards with etchant; the process has become commercially obsolete since it is not as fast as spray etching. In spray etching, the etchant solution is distributed over the boards by nozzles, and recirculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and etchant composition gives predictable control of etching rates and high production rates.
Example Output:
What non-professionals might use immersion etching, since it's the easiest way to make a PCB?