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.

As of 2011, there have been six series — Digimon Adventure, the follow-up sequel Digimon Adventure 02, Digimon Tamers, Digimon Frontier, Digimon Data Squad and Digimon Fusion. The first two series take place in the same fictional universe, but the third, fourth, fifth and sixth each occupy their own unique world. Each series is commonly based on the original storyline but things are added to make them unique. However, in Tamers, the Adventure universe is referred to as a commercial enterprise — a trading card game in Japan, plus a show-within-a-show in the English dub. It also features an appearance by a character from the Adventure universe. In addition, each series has spawned assorted feature films. Digimon still shows popularity, as new card series, video games, and movies are still being produced and released: new card series include Eternal Courage, Hybrid Warriors, Generations, and Operation X; the video game, Digimon Rumble Arena 2; and the previously unreleased movies Revenge of Diaboromon, Runaway Locomon, Battle of Adventurers, and Island of Lost Digimon. In Japan, Digital Monster X-Evolution, the eighth TV movie, was released on January 3, 2005, and on December 23, 2005 at Jump Festa 2006, the fifth series, Digimon Savers was announced for Japan to begin airing after a three-year hiatus of the show. A sixth television series, Digimon Xros Wars, began airing in 2010, and was followed by a second season, which started on October 2, 2011 as a direct sequel to Digimon Xros Wars.
How many series have aired since 2011?

Historically, the name Armenian has come to internationally designate this group of people. It was first used by neighbouring countries of ancient Armenia. The earliest attestations of the exonym Armenia date around the 6th century BC. In his trilingual Behistun Inscription dated to 517 BC, Darius I the Great of Persia refers to Urashtu (in Babylonian) as Armina (in Old Persian; Armina (    ) and Harminuya (in Elamite). In Greek, Αρμένιοι "Armenians" is attested from about the same time, perhaps the earliest reference being a fragment attributed to Hecataeus of Miletus (476 BC). Xenophon, a Greek general serving in some of the Persian expeditions, describes many aspects of Armenian village life and hospitality in around 401 BC. He relates that the people spoke a language that to his ear sounded like the language of the Persians.
How long ago has the term 'Armenia' been used?

Part of the phonological study of a language therefore involves looking at data (phonetic transcriptions of the speech of native speakers) and trying to deduce what the underlying phonemes are and what the sound inventory of the language is. The presence or absence of minimal pairs, as mentioned above, is a frequently used criterion for deciding whether two sounds should be assigned to the same phoneme. However, other considerations often need to be taken into account as well.
What type of language study involves trying to deduce underlying phonomes?