문제 내용: Johannes Kepler believed that there would one day be "celestial ships with sails adapted to the winds of heaven" navigating the sky, filled with explorers "who would not fear the vastness" of space. And today those explorers, human and robot, employ as unerring guides on their voyages through the vastness of space the three laws of planetary motion that Kepler uncovered during a lifetime of personal travail and ecstatic discovery.
선택지 1: faultless
선택지 2: unreliable
선택지 3: gutless
선택지 4: unscientific