Input: Read this: Authorized headdress for the Canadian Armed Forces are the: beret, wedge cap, ballcap, Yukon cap, and tuque (toque). Each is coloured according to the distinctive uniform worn: navy (white or navy blue), army (rifle green or "regimental" colour), air force (light blue). Adherents of the Sikh faith may wear uniform turbans (dastar) (or patka, when operational) and Muslim women may wear uniform tucked hijabs under their authorized headdress. Jews may wear yarmulke under their authorized headdress and when bareheaded. The beret is probably the most widely worn headgear and is worn with almost all orders of dress (with the exception of the more formal orders of Navy and Air Force dress), and the colour of which is determined by the wearer's environment, branch, or mission. Naval personnel, however, seldom wear berets, preferring either service cap or authorized ballcaps (shipboard operational dress), which only the Navy wear. Air Force personnel, particularly officers, prefer the wedge cap to any other form of headdress. There is no naval variant of the wedge cap. The Yukon cap and tuque are worn only with winter dress, although clearance and combat divers may wear tuques year-round as a watch cap. Soldiers in Highland, Scottish, and Irish regiments generally wear alternative headdress, including the glengarry, balmoral, tam o'shanter, and caubeen instead of the beret. The officer cadets of both Royal Military Colleges wear gold-braided "pillbox" (cavalry) caps with their ceremonial dress and have a unique fur "Astrakhan" for winter wear. The Canadian Army wears the CG634 helmet.
Question: What is the least popular head dress worn?

Output: unanswerable

Input: Read this: The Wayback Machine is a digital archive of the World Wide Web and other information on the Internet created by the Internet Archive, a nonprofit organization, based in San Francisco, California, United States. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet. The service enables users to see archived versions of web pages across time, which the archive calls a "three dimensional index."
Question: What is the term used by Internet Archive to describe the Wayback Machine?

Output: three dimensional index

Input: Read this: where a single prime denotes the real part and a double prime the imaginary part, Z() is the complex impedance with the dielectric present, Ccmplx() is the so-called complex capacitance with the dielectric present, and C0 is the capacitance without the dielectric. (Measurement "without the dielectric" in principle means measurement in free space, an unattainable goal inasmuch as even the quantum vacuum is predicted to exhibit nonideal behavior, such as dichroism. For practical purposes, when measurement errors are taken into account, often a measurement in terrestrial vacuum, or simply a calculation of C0, is sufficiently accurate.)
Question: Under what condition is the approximation C0 sufficiently accurate for calculation purposes?

Output: in terrestrial vacuum

Input: Read this: Perceived quality can be influenced by listening environment (ambient noise), listener attention, and listener training and in most cases by listener audio equipment (such as sound cards, speakers and headphones).
Question: Listening environment, listener attention, listener training and listener audio equipment can all affect what kind of quality?

Output:
Perceived quality