Question: Where does the amazon river start and finish?

Disambiguated questions and answers:
context: No context provided
question: Where does the Amazon river start and end?
short_answers: Mantaro River and Atlantic Ocean

context: No context provided
question: Where was it commonly believed the Amazon river started and finished?
short_answers: Apurímac River on Nevado Mismi and Atlantic Ocean

context: A 2014 study by Americans James Contos and Nicolas Tripcevich in "Area", a peer-reviewed journal of the Royal Geographical Society, however, identifies the most distant source of the Amazon as actually being in the Río Mantaro drainage. A variety of methods were used to compare the lengths of the Mantaro river vs. the Apurímac river from their most distant source points to their confluence, showing the longer length of the Mantaro. Then distances from Lago Junín to several potential source points in the uppermost Mantaro river were measured, which enabled them to determine that the Cordillera Rumi Cruz was the most distant source of water in the Mantaro basin (and therefore in the entire Amazon basin). The most accurate measurement method was direct GPS measurement obtained by kayak descent of each of the rivers from their source points to their confluence (performed by Contos). Obtaining these measurements was difficult given the class IV–V nature of each of these rivers, especially in their lower "Abyss" sections. Ultimately, they determined that the most distant point in the Mantaro drainage is nearly 80 km farther upstream compared to Mt. Mismi in the Apurímac drainage, and thus the maximal length of the Amazon river is about 80 km longer than previously thought. Contos continued downstream to the ocean and finished the first complete descent of the Amazon river from its newly identified source (finishing November 2012), a journey repeated by two groups after the news spread.
question: Where is the source of the Amazon River?
short_answers: Río Mantaro

Huancayo, Huancayo Province, Peru
wikipage: Amazon River

context: No context provided
question: Where is the mouth of the Amazon River?
short_answers: Atlantic Ocean

Brazil

Long answers:
knowledge: content: The most distant source of the Amazon was thought to be in the Apurímac river drainage for nearly a century...A 2014 study by Americans James Contos and Nicolas Tripcevich in Area, a peer-reviewed journal of the Royal Geographical Society, however, identifies the most distant source of the Amazon as actually being in the Río Mantaro drainage.
wikipage: Amazon River Origins

content: The Amazon River (UK: /ˈæməzən/, US: /ˈæməzɒn/; Spanish: Río Amazonas, Portuguese: Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river in the world.
wikipage: Amazon River Origins

content: The Apurímac River (Spanish: Río Apurímac, IPA: [ˈri.o apuˈɾimak]; from Quechua apu 'divinity' and rimaq 'oracle, talker') rises from glacial meltwater of the ridge of the Mismi, a 5,597-metre-high (18,363 ft) mountain in the Arequipa Province in the south-western mountain ranges of Peru, 10 km (6.2 mi) from the village Caylloma, and less than 160 km (99 mi) from the Pacific coast. 
wikipage: Apurímac River
long_answer: The Amazon River, located in South America, is the largest river by discharge volume of water in the world. It is also one of the world's longest rivers. For nearly a century, the start and end of the river was considered to be the Apurímac River on Nevado Mismi and Atlantic Ocean. However, a 2014 study identified the most distant source of the Amazon as actually being in the Río Mantaro, located in the central region of Peru. This means the Amazon River starts and ends in the Mantaro River and Atlantic Ocean, respectively. 

knowledge: content: The Amazon River (UK: /ˈæməzən/, US: /ˈæməzɒn/; Spanish: Río Amazonas, Portuguese: Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river in the world.[2][6][n 2]
wikipage: Amazon River

content: The river runs through the provinces Junín, Yauli, Jauja, Concepción and Huancayo in the Junín Region, then through the Huancavelica Region and the Ayacucho Region.
wikipage: Mantaro River Geography
long_answer: The Amazon River in South America is the largest river by discharge volume of water in the world, and the disputed longest river in the world. The Amazon River starts and ends at the Mantaro River and Atlantic Ocean. The Mantaro River, or Río Mantaro, runs through Huancayo Province in Peru. It is commonly believed that the Amazon River started and finished at the Apurímac River on Nevado Mismi and Atlantic Ocean. The mouth of the Amazon River is in Brazil at the Atlantic Ocean.