A.I. Explanation:

Option 1: "Explorer I was a failure, since scientists had to create IRAS in order to figure out many mysteries of the universe."

Explanation: This option misrepresents the author's view. The text does not suggest that Explorer 1 was a failure; rather, it highlights its success in discovering the Van Allen radiation belts. The creation of IRAS is presented as a continuation of progress in satellite technology, not as a necessity due to Explorer 1's failure.

Option 2: "Scientific satellites have eventually fulfilled scientists’ expectations."

Explanation: This option accurately reflects the author's opinion. The text states that scientists anticipated the benefits of satellites and confirms that these expectations were met, as evidenced by the discoveries made by Explorer 1 and IRAS. The phrase 'have eventually fulfilled' aligns with the overall theme of the text, which emphasizes the success of scientific satellites.

Option 3: "The Infrared Astronomy Satellite has been one of the best satellites created by the United States."

Explanation: While the text mentions IRAS as a significant satellite, it does not label it as 'one of the best.' This option introduces a subjective judgment that is not supported by the text. The focus is on the contributions of IRAS rather than a comparative evaluation of its quality.

Option 4: "Orbiting satellites existed before the Russian satellite Sputnik."

Explanation: This option is factually incorrect. The text indicates that Sputnik was the first satellite, implying that no orbiting satellites existed before it. Therefore, this statement contradicts the information provided in the text.