Read about several discoveries conducted by Russian scientists in the last 20 years. Match each discovery with the suitable branch of science. There is one extra branch.

Write one letter in each gap.

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In 2002 and 2003, Russian mathematician Grigori Perelman developed new techniques in mathematical analysis and proved the Poincaré conjecture and Thurston's geometrisation conjecture, the former of which had been a famous open problem in mathematics for the past century.

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Russian doctors and scientists have developed and created the world's first artificial left ventricle of the heart. It is necessary for children with irreversible defects, chronic insufficiency, and other heart problems, who need a transplant, but according to age and physical characteristics, are not suitable for it yet.

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Russian scientists came up with new hypotheses about human migration on Earth. The results of the study of the folklore and myths of the peoples of Siberia and America have shown the possibility of determining the directions of the movements of the primitive tribes. These data are confirmed by archaeological excavations and genetic science.

A. Anthropology

B. Mathematics

C. Astronomy

D. Medicine