Question: Of the two fottballer O'Leary brothers, which is the oldest?

Context paragraphs:
Two If by Sea: Two If by Sea (also known in the United Kingdom as Stolen Hearts) is a 1996 American romantic comedy film directed by Bill Bennett, and starring Sandra Bullock and Denis Leary.  The screenplay, written by Leary and Mike Armstrong, is based on a story by Leary, Armstrong, and Ann Lembeck.

Pierce O'Leary: Pierce O'Leary (born 5 November 1959 in Dublin) is an Irish former professional footballer.  Pierce is the brother of former Arsenal star and fellow Irish international David O'Leary.

Leary School: Leary School of Alexandria, Virginia, is one of two campuses operated by the Lincolnia Educational Foundation, Inc., a non-public, non-profit organization.  The other campus is located in Oxon Hill, Maryland.  The Leary Schools are special-education schools that together serve over 200 students with emotional, behavioral and learning problems annually.  Timber Ridge School, a residential treatment center in Cross Junction, Virginia, exists for boys age 10-17 requiring treatment in a 24-hour-a-day environment.

Michael John O'Leary: Major Michael John O'Leary VC (29 September 1890 – 2 August 1961) was an Irish recipient of the Victoria Cross, the most prestigious award for gallantry in the face of the enemy that can be awarded to British and Commonwealth forces.  O'Leary achieved his award for single-handedly charging and destroying two German barricades defended by machine gun positions near the French village of Cuinchy, in a localised operation on the Western Front during the First World War.

Monument Ave. (film): Monument Ave., originally titled Snitch in the United States and titled Noose in Australia, is a 1998 American crime comedy-drama film directed by Ted Demme and starring Denis Leary.  The film also stars Famke Janssen, Martin Sheen, Ian Hart, and Lenny Clarke.  Cam Neely also makes a brief appearance as a man returning home from work who finds his house has been broken into.  The film takes place in Charlestown, Massachusetts and centers on small-time criminal Bobby O'Grady (Leary), who becomes conflicted due to Charlestown's code of silence when his loyalty and drive for self-preservation are tested after two of his close family members (also criminals) are gunned down by their boss.

David O'Leary: David Anthony O'Leary (born 2 May 1958) is an Irish football manager and former player.  His managerial career began at Leeds United and later he managed Aston Villa.  He most recently worked as the manager of Al-Ahli Dubai.  The majority of his 20-year playing career was spent as a central defender at Arsenal.  O'Leary's tally of 722 appearances for the North London side stands as a club record.

Harvard Psilocybin Project: The Harvard Psilocybin Project was a series of experiments in psychology conducted by Dr. Timothy Leary and Dr. Richard Alpert.  The founding board of the project consisted of Leary, Aldous Huxley, David McClelland (Leary's superior at Harvard University), Frank Barron, Ralph Metzner, and two graduate students who were working on a project with mescaline.  The experiments began some time in 1960 and lasted until March 1962, when other professors in the Harvard Center for Research in Personality raised concerns about the legitimacy and safety of the experiments in an internal meeting.

Sara O'Leary: Sara O'Leary is a Canadian writer.  She has published fiction, children's books, plays, and criticism.  She is married to the poet and academic Daniel O’Leary and they have two sons.  She holds an MA in English and Creative Writing from Concordia University in Montreal and an MFA with a specialization in Screenwriting from the Program in Theatre, Film and Creative Writing at the University of British Columbia.

Joe O'Leary: Michael Joseph "Joe" O'Leary (29 September 1883 – 12 December 1963) was a New Zealand rugby union player.  Primarily a fullback, O'Leary represented Wairarapa, Wellington , and Auckland at a provincial level.  He was a member of the New Zealand national side, the All Blacks, in 1910 and 1913.  He played eight matches for the All Blacks, including four internationals, of which two were as captain against the touring Australian team in 1913.

O'Leary Manager 2000: O'Leary Manager 2000 is a football player-manager game released in 2000 for the Game Boy Color.  The player can choose whether they want to focus on the management side of football, play the matches themselves on the game's 2D match engine, or combine the two features for a more in-depth experience.  It is endorsed by Irish football manager David O'Leary, who was managing Leeds United A.F.C. at the time of the game's release.

Supporting paragraphs: Pierce O'Leary David O'Leary
Answer: David O'Leary