Question: Mexico is led by a chief of state who is?

Disambiguated questions and answers:
context: No context provided
question: Mexico is led by a chief of state whose title is?
short_answers: president of Mexico

president of the United Mexican States

context: Peña Nieto was sworn-in as President of Mexico on 1 December 2012 at the federal congress and later flew to a military parade to formally take control of the armed forces. During his inauguration speech at the National Palace, Peña Nieto proposed his agendas and reforms for the new administration. Before and after the inauguration, in an event that has been labeled by the media as the "1DMX", protesters rioted outside of the National Palace and clashed with Federal Police forces, vandalizing hotel structures and setting fires in downtown Mexico City. More than 90 protesters were arrested and several were injured. Mayor Marcelo Ebrard blamed anarchist groups for the violence. However, there is evidence that agents of provocation worked with the police, paid 300 Mexican pesos (about US$20) for their acts of vandalism, according to media reports. Photos show the vandals waiting in groups behind police lines prior to the violence. Previous protests had been entirely peaceful, but on this occasion, in apparent response to violence, the police fired rubber bullets. The day after his inauguration, Peña Nieto announced the Pact for Mexico, an agreement that he had struck with the leaders of the two other major parties at the time, Jesús Zambrano Grijalva of the Party of the Democratic Revolution and Gustavo Madero Muñoz of the National Action Party, about the government's goals for the next few years. On December 1, 2018, Enrique Peña Nieto left office and was succeeded by Andrés Manuel López Obrador.
question: Mexico is led by which chief of state from 2012 to 2018?
short_answers: Enrique Peña Nieto

EPN
wikipage: Enrique Peña Nieto

context: Felipe de Jesús Calderón Hinojosa, (; born 19 August 1962) is a Mexican politician who served as the 56th President of Mexico from 1 December 2006 to 30 November 2012. He was a member of the National Action Party ("Partido Acción Nacional", PAN) for thirty years before quitting the party in November 2018.
question: Mexico is led by which chief of state from 2006 to 2012?
short_answers: Felipe de Jesús Calderón Hinojosa

Felipe Calderón
wikipage: Felipe Calderón

context: On November 30, 2006, outgoing President Vicente Fox Quesada and still President-elect Felipe Calderón Hinojosa stood side-by-side on national television as Fox turned over the presidential sash to a cadet, who handed it to Calderón. Afterwards, Fox read a short speech indicating that he had concluded his mandate by receiving the flag "that had accompanied him during the last six years which he had devoted himself completely to the service of Mexico and had the utmost honor of being the president of the republic". Calderón then made a speech to the Mexican public indicating that he would still attend the inauguration ceremony at the Chamber of Deputies. He made a call to unity.
question: Mexico is led by which chief of state from 2000 to 2006?
short_answers: Vicente Fox

Vicente Fox Quesada
wikipage: Felipe Calderón

Long answers:
knowledge: content: The president of Mexico (Spanish: Presidente de México), officially known as the president of the United Mexican States (Spanish: Presidente de los Estados Unidos Mexicanos),[2] is the head of state and head of government of Mexico. Under the Constitution of Mexico, the President is the chief of the executive branch of the federal government and is the commander in chief of the Mexican Armed Forces. The current president is Andrés Manuel López Obrador, who took office on 1 December 2018.
wikipage: President of Mexico

content: Mexican presidents are limited to a single six-year term, called a sexenio.
wikipage: President of Mexico
long_answer: The president of Mexico is the head of state and head of government of Mexico. Under the Constitution of Mexico, the President is the chief of the executive branch of the federal government and is the commander in chief of the Mexican Armed Forces. The current president is Andrés Manuel López Obrador, who took office on 1 December 2018. Enrique Peña Nieto was President from 2012 to 2018, Felipe de Jesús Calderón Hinojosa was President from 2006 to 2012, and Vicente Fox Quesada was President from 2000 to 2006. Mexican presidents are limited to a single six-year term.