Question: Astral Oil Works became part of which branch that was owned by wealthiest American of all time?
Context: Wilhelm Heinrich Detlev "Big Bill" Körner (November 1878 – August 11, 1938), also known as Wilhelm Heinrich Dethlef Koerner, William HD Koerner, WHDK, or W.H.D. Koerner, was a noted illustrator of the American West whose works became known to new audiences when his painting, nicknamed "A Charge to Keep", was used as the cover image for the ghostwritten biography by the same name by George W. Bush.  This painting, which hung in the Oval Office during the Bush presidency was of special interest to journalists due to the interpretation given by Bush of the painting's meaning in light of the meaning and title attached to the painting by the artist. The Sioux City Linseed Oil Works is a historic building located in Sioux City, Iowa, United States.  It is located in an area east of the central business district where warehouses and other industrial buildings are located.  It housed the Sioux City Linseed Oil Works (initially known as Hubbard and Gere) from 1884, when it was built, until 1927 when its owner, the American Linseed Oil Company, ceased production here.  The building was largely destroyed in a fire that began late in the night of May 20, 1891.  Mankato, Minnesota architect William D. McLaughlin stepped in to complete the work begun by Sioux City architect E.W. Loft.  Essentially, the building was rebuilt and was very similar in appearance to the original structure.  Gone was the gable roof on the westernmost wing, which was replaced by a flat roof, and two floors were added to the rebuilt press room annex in the back.  The building was acquired by Bekins Van and Storage Company in 1928.  They began operations here two years later, and they remained the primary tenant in the building until 1972.  There was a variety of other tenants who were housed here over the years.  The building was listed on the National Register of Historic Places in 2008. Herbert Lee Pratt (November 21, 1871 – February 3, 1945) was an American businessman and a leading figure in the United States oil industry.  In 1923, he became head of Standard Oil; his father Charles Pratt was a founder of Astral Oil Works, which later became part of Standard Oil.  He lived and worked in New York City, as well as having a country estate, "The Braes" in Glen Cove, Long Island, and a hunting preserve and estate, "Good Hope Plantation" in Ridgeland, South Carolina.  He was also an art collector and philanthropist. John Davison Rockefeller Sr. (July 8, 1839 – May 23, 1937) was an American oil industry business magnate and philanthropist.  Widely considered the wealthiest American of all time and the richest person in modern history, Rockefeller was born into a large family in upstate New York and was shaped by his con man father and religious mother.  His family moved several times before eventually settling in Cleveland, Ohio. Deans is a small community within the town of Livingston in West Lothian, Scotland.  Deans is situated in the northern part of Livingston, The western area of Deans was formerly known as Livingston Station, as it is the location of former oil works and a railway station.  Many people who have lived in this area for a long time often refer to it as such.  In 2010 the population of Deans was 3,641 Baltimore Chrome Works was a chromium ore refinery with its headquarters and main factory located at Fells Point, Baltimore, USA.  Isaac Tyson started mining chromite in the area around Baltimore in 1813 and built the Baltimore Chrome Works at Fells Point in 1845.  The works became part of Mutual Chemical Company in 1908, and merged into Allied Chemical in 1954.  The plant, which was rebuilt in 1951, employed 375 people at peak production. Astral Oil Works was an American oil company specializing in illuminating oil, and based in Brooklyn, New York.  Astral Oil was a high-quality kerosene used in lamps and noted for being relatively safe.  It was founded by Charles Pratt.  Charles Pratt and Company (including Astral Oil) became part of John D. Rockefeller’s Standard Oil Trust in 1874, although the fact that Astral Oil was a New York branch of Standard Oil in Ohio was not made public until 1892. Balázs Havasi (born 18 September 1975) is a Hungarian pianist and composer.  As a contemporary composer he has launched four completely different musical projects, including compositions for a symphony orchestra, rock drums and piano.  Havasi wrote a song for singer Tracey Thorn and gave a speech at the TED Global conference about his efforts in musical innovation.  He is known for his fondness of Asian culture and martial arts, which he practiced for years.  Havasi’s works became known to millions within a short time. Max I. Silber (February 15, 1911 – June 15, 2004) was an American businessman from New Hampshire who through his philanthropic works became not only a formative figure for Boy Scouting in New Hampshire, but a distinguished citizen of his home state.  A devout Jew, Silber was an active supporter of religious Scouting programs, and was distinguished not just by the Jewish Committee of Scouting, but by the Roman Catholic Committee on Scouting as well.  Perhaps the most famous endeavor of Silber's was the development of his "friendship gifts" which were most commonly belt buckles made of bronze.  These buckles have evolved into popular Scouting collectibles. Pennzoil is an American oil company founded in Los Angeles, California in 1913.  In 1955, it was acquired by Oil City, Pennsylvania company South Penn Oil, a former branch of Standard Oil.  In 1963, South Penn Oil merged with Zapata Petroleum; the merged company took the Pennzoil name.  In 1968 United Gas Corporation became part of Pennzoil.  (Although United Gas was a larger company, pre-merger, Pennzoil had successfully used a "leveraged buyout" strategy.)  During the 1970s, the company moved its offices to Houston, Texas.  In 1977 a spin-off company was formed called Pogo, which stood for Pennzoil Offshore Gas Operators.
Answer: Standard Oil Trust