Question: What is the main opposition party to the President of Nigeria?

Context paragraphs:
Opposition day: An opposition day is a day in a legislature using the Westminster System in which an opposition party sets the agenda.  Most days the parliamentary agenda is set by the government; opposition days allow the smaller parties to choose the subject for debate.  The number of days varies between parliaments.  In the United Kingdom there are twenty opposition days per parliamentary session, and in Canada there are twenty-two.  The days are divided among opposition parties with the Official Opposition allotted the most; In the UK, the Official Opposition party is given 17 opposition days, and the second biggest opposition party given 3 days.  Canadian opposition parties are allocated days, which are also called "allotted" or "supply" days, in proportion to their membership in the House.  There are no opposition days in Australian jurisdictions.  In India, the Parliament does not have an opposition day, but every week, one day (every Friday) during a session, is devoted to Private members bills and resolutions.

Muhammadu Buhari: Muhammadu Buhari {'1': ", '2': ", '3': 'GCFR', '4': "} (born 17 December 1942) is the President of Nigeria, in office since 2015.  He is a retired major general in the Nigerian Army and previously served as the nation's head of state from 31 December 1983 to 27 August 1985, after taking power in a military "coup d'état".  The term Buharism is ascribed to the Buhari military government.

Shadow Cabinet (National Assembly for Wales): Unlike the Westminster arrangement where there is an 'Official Opposition' to the government of the day, there is no such thing as an 'official' opposition to the Welsh Government.  Instead, all parties that are not in government are merely 'opposition parties'.  With the current Welsh Government being a minority government run by Welsh Labour, the main opposition party from May – mid October was Plaid Cymru but after one of Plaids Assembly Members resigned from the party, it had equally the same seats as the Welsh Conservatives therefore lost the title of the official opposition.

Northern Elements Progressive Union: The Northern Elements Progressive Union (NEPU) was the first political party in Northern Nigeria.  Founded in Kano on 8 August 1950, it was the offshoot of a pre-existing political association called the Northern Elements Progressive Association.  It became the main opposition party in Northern Nigeria after the region was granted self-governance in the 1950s.  In the First Republic it maintained a steady alliance with Zikist National Council of Nigeria and the Cameroons (NCNC) against the Northern People's Congress (NPC)-dominated Federal Government.

Leader of the Opposition (Sri Lanka): The Leader of the Opposition in Sri Lanka is the politician who leads the main opposition party.  This is the leader of the largest party not within the government, usually the leader of the second largest party in the Parliament.  The post of Leader of the Opposition is a political office common in countries that are part of the Commonwealth of Nations.

Jean-Pierre Fabre: Jean-Pierre Fabre (born 2 June 1952) is a Togolese politician and the President of Togo's main opposition party, the National Alliance for Change ("Alliance Nationale pour le Changement", ANC).  He served for years as Secretary-General of the Union of the Forces of Change (UFC), and he was President of the UFC Parliamentary Group in the National Assembly from 2007 to 10 August 2010.  He stood as the main opposition presidential candidate in 2010 and again in 2015.

United Party (Ghana): The United Party was the main opposition party in the First Republic of Ghana.  It was the only opposition party throughout its existence from 1957 until 1964 when Ghana became a one party state.

Official Opposition Shadow Cabinet (Canada): The Official Opposition Shadow Cabinet in Canada is composed of members of the main opposition party, Her Majesty's Loyal Opposition, and is responsible for holding the Government to account and for developing and disseminating the party's policy positions.  Members of the official opposition are generally referred to as opposition critics, but the term Shadow Minister (which is generally used in other Westminster systems) is also used.

Aisha Alhassan: Aisha Jummai Al-Hassan, popularly known as Mama Taraba is a Nigerian politician.  She is the Minister of Women Affairs of Nigeria.  She was appointed in 2015 to the cabinet of President Muhammadu Buhari after his election.  She was previously a Senator, representing Taraba North constituency of Taraba State, Nigeria which she won under the platform of the People's Democratic Party (PDP).  She later decamped to the main opposition party All Progressive Congress (APC) and became the Gubernatorial Candidate of Taraba State for the 2015 general elections.  She was defeated in the election re-run held on 25th of April 2015, but on 7 November 2015 tribunal removes Taraba Governor, Darius Ishaku,

New Democratic Party (South Korea): The New Democratic Party of Korea (Korean: 신민당, hanja: 新民黨; NDP) was a South Korean opposition party that existed from 1963 to 1980, when it was forcibly dissolved by the ninth amendment of the constitution promulgated by Chun Doo-hwan the same year.  It was the main opposition party during the Park Chung-hee dictatorial regime, and especially since 1972, when the Yushin constitution was put into effect.

Supporting paragraphs: Aisha Alhassan Muhammadu Buhari
Answer: All Progressive Congress (APC)