The correct answer is C. Yuri Gagarin was a Russian cosmonaut who became the first man to travel in space. He was launched on April 12, 1961, on a Vostok 1 spacecraft and orbited the Earth once before returning safely to Earth. His flight was a major achievement for the Soviet Union and helped to spur the Space Race between the United States and the Soviet Union.
Option A is correct because Yuri Gagarin was a Russian cosmonaut. He was born in the village of Klushino in the Smolensk Oblast of the Russian Soviet Federative Socialist Republic on March 9, 1934. He joined the Soviet Air Force in 1955 and became a fighter pilot. In 1960, he was selected to be one of the first cosmonauts in the Soviet space program.
Option B is incorrect because Yuri Gagarin was not the first person to fly at great height. The first person to fly at great height was Auguste Piccard, who flew in a balloon to an altitude of 53,000 feet in 1931.
Option D is incorrect because Yuri Gagarin was both a Russian cosmonaut and the first man to travel in space.