  Aviation is the field concerned with the design, development, and operation of aircraft.

  Celestial (A) refers to anything related to the sky or heavens, not airplanes.

  Diarchy (B) refers to a government system ruled by two people.

  Aeronautics (C) refers to the science of flight, but aviation is the more common term for the study of flying airplanes.

  Archaic refers to something that is very old or outdated.

  Dotage (A) refers to the period of life when a person is elderly and weak, but it does not mean "old-fashioned."

  Odd (B) means unusual, not necessarily old or outdated.

  Gourmet (C) refers to a person who enjoys and understands fine food, not related to being old-fashioned.

  Auctioneer is the person who conducts an auction, selling goods to the highest bidder.

  Wholesaler (A) sells goods in bulk, usually to retailers, not at auctions.

  Market (B) refers to a place where goods are bought and sold, not the person.

               Barter (D) is the exchange of goods or services without money, not related to auctions.

  Terrorism refers to the unlawful use of violence or intimidation, especially against civilians, in the pursuit of political aims.

  Turmoil (B) refers to a state of great confusion or disorder, not specifically violence for political aims.

  Blackmail (C) is the act of demanding money or other favors through threats.

  Notorious (D) describes someone famous for bad reasons, not an act of violence.

  Author is a person who writes books, articles, or other written works.

  Bibliography (A) is a list of books or written works.

  Autobiography (B) is a book written by someone about their own life.

               Playwright (D) is someone who writes plays, not books in general.

  Aristocracy refers to a form of government where power is held by a privileged class, typically the nobility or wealthy elites.

  Democracy (A) is a government by the people, where everyone has a say.

  Autocracy (B) refers to a government controlled by one person with absolute power.

  Bureaucracy (C) is a system of government where decisions are made by state officials, not elected representatives.

·      Panacea refers to a remedy that can cure all diseases or problems.

·      Cure (B) is a general term for something that heals a disease but doesn’t mean a universal cure for all.

·      Antibiotic (C) is a substance that kills or inhibits the growth of bacteria, but it's not a cure for all diseases.

·      Remedy (D) refers to a treatment or solution for a particular problem, not a universal one.

  Smog refers to a mixture of smoke and fog that reduces air quality and transparency.

  Vapor (A) refers to gas-like water, which is not necessarily suspended in the air to impair transparency.

  Substance (B) is too broad a term and doesn't describe air pollution.

  Cloud (D) is a collection of water droplets or ice crystals in the atmosphere but doesn’t necessarily impair transparency in the same way as smog.

  Anthropologist is someone who studies the development, culture, and evolution of humans.

  Funambulist (B) is a tightrope walker.

  History (C) is the study of past events, not specifically about human evolution.

  Philistine (D) refers to a person who is indifferent to culture or the arts, not someone studying mankind.

  Astronomer is someone who studies celestial bodies such as stars, planets, and galaxies.

  Constellation (A) is a group of stars, not a person.

  Ornithology (B) is the study of birds, not heavenly bodies.

  Geology (C) is the study of the Earth's structure and substances, not the stars.