Please answer the following question: Information:  - The Party of European Socialists (PES) is a social-democratic European political party. The PES comprises national-level political parties primarily from member states of the European Union (EU) and other nations of the European continent. The PES member parties are themselves mostly members of the Progressive Alliance or Socialist International. The political group in the European Parliament of the PES is the Progressive Alliance of Socialists and Democrats (S&D). The PES also operates in the Committee of the Regions (in the PES Group in the Committee of the Regions) and the European Council. The PES is currently led by Sergei Stanishev, former Prime Minister of Bulgaria.  - A president is the leader of a country or a division or part of a country, typically a republic, a democracy, or a dictatorship. The title "president" is sometimes used by extension for leaders of other groups, including corporate entities and social groups.  - Anders Fogh Rasmussen (born 26 January 1953) is a Danish politician who was the 39th Prime Minister of Denmark from November 2001 to April 2009 and the 12th Secretary General of NATO from August 2009 to October 2014.  - Arne Rolighed ( born 2 June 1947 ) is a Danish former politician and the current president of the Danish Cancer Society until July 2010 . Although he was never a member of the Danish parliament , Prime minister Poul Nyrup Rasmussen appointed him as Health Minister in December 2000 , a position he held until the Social Democratic government lost the 2001 parliamentary election to Venstre 's Anders Fogh Rasmussen .  - The Prime Minister of Denmark (literally "Minister of State") is the head of government in the Kingdom of Denmark. Before the creation of the modern office, Denmark did not initially have a head of government separate from its head of state, namely the Monarch, in whom the executive authority was vested. The Constitution of 1849 established a constitutional monarchy by limiting the powers of the Monarch and creating the office of . The inaugural holder of the office was Adam Wilhelm Moltke.  - The European Parliament (EP) is the directly elected parliamentary institution of the European Union (EU). Together with the Council of the European Union (the Council) and the European Commission, it exercises the legislative function of the EU. The Parliament is composed of 751 (previously 766) members, who represent the second largest democratic electorate in the world (after the Parliament of India) and the largest trans-national democratic electorate in the world (375 million eligible voters in 2009).  - The North Atlantic Treaty Organization (NATO  '), also called the North Atlantic Alliance, is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4 April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defence in response to an attack by any external party. Three NATO members are permanent members of the United Nations Security Council with the power to veto and are officially nuclear-weapon states: the United States, France and the United Kingdom. NATO's headquarters are located in Haren, Brussels, Belgium, where the Supreme Allied Commander also resides. Belgium is one of the 28 member states across North America and Europe, the newest of which, Albania and Croatia, joined in April 2009. An additional 22 countries participate in NATO's Partnership for Peace program, with 15 other countries involved in institutionalized dialogue programmes. The combined military spending of all NATO members constitutes over 70% of the global total. Members' defence spending is supposed to amount to 2% of GDP.  - Poul Oluf Nyrup Rasmussen (informally Poul Nyrup, born 15 June 1943), was Prime Minister of Denmark from 25 January 1993 to 27 November 2001 and President of the Party of European Socialists (PES) from 2004 to 2011. He was the leader of the governing Social Democrats from 1992 to 2002. He was a member of the European Parliament from 2004 to 2009.    After reading the paragraphs above, choose the best answer for the entity that related to 'arne rolighed' with the relationship of 'member of political party'.  Choices: - alliance  - constitutional monarchy  - republic  - social democrats  - union
A:
social democrats