Question: South Improvement Company was one part of which oil magnate's attempts to control this industry?

Context paragraphs:
Clint Murchison Sr.: Clinton Williams "Clint" Murchison Sr. (April 11, 1895 – June 20, 1969) was a noted Texas-based oil magnate and political operative.  Among his companies was the Southern Union Company.  He was also the father of Dallas Cowboys owner Clint Murchison Jr..

UU Bar Ranch: The Express UU Bar Ranch, formerly owned by Oklahoma oil magnate Waite Phillips, is now owned by Express Ranches (headquartered in Yukon, Oklahoma).  The UU Bar Ranch is west of Cimarron, New Mexico and is south of Philmont Scout Ranch.  The two ranches are separated by Highway 21.  Express Ranches is controlled by Robert A. "Bob" Funk, who is chairman, CEO, and founder of Express Employment Professionals.

Rockefeller Park: Rockefeller Park is a city park named in honor of oil magnate John D. Rockefeller Sr., located in Cleveland, Ohio.  Part of the Cleveland Public Parks District, Rockefeller Park is immediately adjacent Wade Park to the southeast, and across Euclid Ave on its northwest border.  Besides the distinction of being the largest park located completely within city limits, Rockefeller Park is a link in a chain of parkland that connects the heights region of the eastern suburbs to the city's lakefront.  Following the path of Martin Luther King Jr.  Drive and spanning a large section of Cleveland's East Sides, the park runs in a northwesterly path between suburban Shaker Heights, bisecting the University Circle neighborhood and terminating at Gordon Park on the city's lakefront, opened to the public in 1897.

Fredrick Obateru Akinruntan: Fredrick Obateru Akinruntan (born 1950) is a Nigerian monarch, the traditional ruler of Ugbo Kingdom, a town in Ilaje Local Government, Ondo State, southwestern Nigeria.  He is an oil magnate and founder of Obat Oil, one of Nigeria's largest and leading privately held oil companies.

LaQuinta: LaQuinta is a historic house in Bartlesville, Oklahoma, United States.  It was built in 1930 for oil magnate H.V. Foster.  The Spanish Colonial Revival house, now part of Oklahoma Wesleyan University, was listed on the National Register of Historic Places in 1982.

South Improvement Company: The South Improvement Company was a Pennsylvania corporation in 1871-1872.  It was created by major railroad interests, but was widely seen as part of John D. Rockefeller's early efforts to organize and control the oil and natural gas industries in the United States which eventually became Standard Oil.  Although it lasted less than a year and never shipped any oil, the South Improvement Company scheme caused widespread attention to be focused on the relationships between big railroads and big businesses which wanted and demanded favorable treatment.

The Casements: The Casements is a mansion in Ormond Beach, Florida, U.S., famous for being the winter residence of American oil magnate John D. Rockefeller.  It is currently owned by the city of Ormond Beach and is used as a cultural center and park.  It is located on a barrier island within the city limits, overlooking the Halifax River, which is now part of the Florida Intracoastal Waterway.

John D. Rockefeller: 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.

Alexander Mantashev: Alexander Mantashev (Armenian: Ալեքսանդր Մանթաշյանց , Aleksandr Mantashiants; Russian: Александр Иванович Манташев , Aleksandr Ivanovich Mantashev; 3 March 1842 – 19 April 1911 and was buried on 30 April in the Armenian Pantheon of Tbilisi) was a prominent Armenian oil magnate, industrialist, financier, and a philanthropist.  By the end of his life he had become one of the world's wealthiest individuals.

Forest Hill, Ohio: Forest Hill is an historic neighborhood spanning parts of Cleveland Heights and East Cleveland, Ohio, and is bordered to the north by Glynn Road, the south by Mayfield Road, by Lee Boulevard to the west and North Taylor Road to the east.  Forest Hill was once the beloved summer home of oil magnate John D. Rockefeller and his family.  John D. Rockefeller, Jr. purchased the estate from his father in 1923 and, with New York City architect Andrew J. Thomas, planned an upscale residential and commercial development featuring distinctive French Norman style architecture.  Although the Great Depression forced Rockefeller to suspend operations, following World War II others were drawn to Forest Hill to build comfortable colonial and contemporary ranch homes on the remaining open land.  Design principles of the Rockefeller-Thomas plan were extended to the later development and today Forest Hill is a rich tapestry of people, homes and gardens.

Supporting paragraphs: South Improvement Company John D. Rockefeller
Answer: John Davison Rockefeller Sr.