A.I. Explanation:

Option 1: "The concept of space travel was only possible in the 21st century."

Explanation: This option is incorrect because the text states that dreams of space travel began long before the 21st century, specifically mentioning the early 20th century with the development of liquid fuel rockets.

Option 2: "RH Goddard launched the first liquid fuel rocket in 1926."

Explanation: This option is correct as the text explicitly states that RH Goddard launched the first liquid fuel rocket in 1926, confirming the historical fact.

Option 3: "The V2 rockets were used for peaceful purposes during World War II."

Explanation: This option is incorrect because the text indicates that the V2 rockets were used in the bombing of London, which clearly shows they were used for military purposes, not peaceful ones.

Option 4: "German scientists contributed to the American Rocket program after World War II."

Explanation: This option is correct as the text mentions that many German scientists moved to the United States after the war and contributed to the American Rocket program, supporting this statement.

Option 5: "Sputnik 1, launched by the Soviet Union in 1957, was the world's first satellite."

Explanation: This option is correct because the text states that Sputnik 1 was launched by the Soviet Union in 1957 and refers to it as the first satellite, confirming its significance in space exploration.

Option 6: "The race to the moon ended with the launch of the first American satellite."

Explanation: This option is incorrect as the text does not state that the race to the moon ended with the launch of the first American satellite; rather, it indicates that the race to the moon began after the launch of Sputnik 1.