Question: The politician who defeated Vincent C. Gray in the primary of 2014 previously served which ward?

Context paragraphs:
Cathy L. Lanier: Cathy Lynn Lanier (born July 22, 1967) was the chief of the Metropolitan Police Department of the District of Columbia (MPDC).  Lanier was appointed by Washington, D.C. Mayor Adrian Fenty in January 2007, replacing outgoing Police Chief Charles H. Ramsey.  She is the first woman to achieve the position.  In May 2012, Mayor Vincent C. Gray agreed to retain Lanier as police chief under a new five-year contract.  On August 16, 2016, it was announced that Lanier would retire from the Metropolitan Police Department of the District of Columbia in September 2016 to become Senior Vice President of Security for the National Football League.  Her last day as Police Chief was September 15, 2016.

Adrian Fenty: Adrian Malik Fenty (born December 6, 1970) is an American politician who served as the sixth mayor of the District of Columbia.  He served one term, from 2007 to 2011, losing his bid for reelection at the primary level to Democrat Vincent C. Gray.  Though Fenty won the Republican mayoral primary as a write-in candidate, he declined the Republican nomination and said he would likely not seek elected office again.  Gray went on to win the general election for Mayor in the largely Democratic District.

Cynthia Brock-Smith: Cynthia Brock-Smith served as the Secretary of the District of Columbia, the equivalent of a Secretary of State, under Mayor Vincent C. Gray.

Irvin B. Nathan: Irvin B. Nathan served as Attorney General of the District of Columbia from 2011 to 2015.  He was appointed in 2011 by Mayor Vincent C. Gray.  He previously served as the General Counsel of the United States House of Representatives from 2007 to 2011.  Nathan announced his resignation the day after the November 2014 election, in which voters chose Karl Racine as the first elected Attorney General of D.C.

Vincent C. Gray: Vincent Condol "Vince" Gray (born November 8, 1942) is an American politician who served as the seventh Mayor of the District of Columbia.  He served one term, from 2011 to 2015, losing his bid for reelection in the Democratic primary to D.C. City Council member Muriel Bowser.  Bowser would go on to win the 2014 election.  Prior to his inauguration as mayor in January 2011, Gray served as Chairman of the Council of the District of Columbia, and as Councilmember for Ward 7.  In the 1990s he also served as director of the DC Department of Human Services.  In June 2016, he defeated incumbent Yvette Alexander in the Democratic primary for the council seat he previously held in Ward 7.

Kenneth B. Ellerbe: Kenneth B. Ellerbe was the Fire Chief of the District of Columbia Fire & EMS Department from January 1, 2011 – July 2, 2014.  He was chosen by then mayor-elect Vincent C. Gray in December 2010.

Muriel Bowser: Muriel Elizabeth Bowser (born August 2, 1972) is an American politician and member of the Democratic Party currently serving as the eighth Mayor of the District of Columbia.  Prior to her inauguration in January 2015, Bowser served as a member of the Council of the District of Columbia, representing Ward 4.

Ruby Corado: Ruby Corado (born in San Salvador, El Salvador) is an activist who founded Casa Ruby, the only bilingual, multicultural LGBT organization in Washington, D.C. Casa Ruby opened in 2012; it identifies its mission as "to create success life stories among Transgender, Gender Queer, and Gender Non-conforming Gay, Lesbian and Bisexual people."  Corado immigrated to America from El Salvador at age sixteen to escape the civil war in El Salvador.  Born Vladimir Artiga, she is a transgender woman, and began transitioning in the 1990s.  Corado was part of the Coalition to Clarify the D.C. Human Rights Act, which changed the D.C. Human Rights Act to include protections for gender identity or expression, a change that took effect in March 2006.  Corado married David Walker in 2014, and was walked down the aisle by D.C. mayor Vincent C. Gray.

Vincent Siew: Vincent C. Siew or Siew Wan-chang (; born 3 January 1939) is a Taiwanese politician who served as the Vice President of the Republic of China from 2008 to 2012.  He was the first Taiwanese-born Premier of the Republic of China and former vice-chairman of the Kuomintang (KMT).

Linda W. Cropp: Linda Washington Cropp (born October 5, 1947) is an American politician from Washington, D.C., the capital of the United States.  She was a Democratic member of the Council of the District of Columbia, where she was the first woman to serve as the elected Council Chairman.  On September 12, 2006, she lost the Democratic Primary for Mayor (57%-31%) to Adrian Fenty.  This loss came in spite of the fact that Cropp had been endorsed by outgoing mayor Anthony A. Williams.  She was succeeded as Council Chairman by Vincent C. Gray.

Supporting paragraphs: Vincent C. Gray Muriel Bowser
Answer: Ward 4