One major goal of NASA's Gemini program was to

Was to get men in space and be the first to the moon, which was later moved to apollo.

The correct answer is "to launch astronauts on long flights."

One major goal of NASA's Gemini program was to launch astronauts on long flights

NASA's Gemini program had four specific goals. The first one, testing astronauts abilities to fly long duration expeditions, two weeks average. The second, to know how the spacecraft could enter the orbit around the moon and the Earth. The third, to train entry and landing procedures. And fourth, learn more about the effects long space expeditions had on astronauts.

The other options of the question were, a) to launch an artificial satellite, b) send manned aircraft into Earth's orbit, and d) land an astronaut on the moon.