This could be false. A large moon may stabilize Mars’s axis tilt angle, fulfilling a necessary condition for life on Mars. However, this does not mean Mars fulfills any other conditions for supporting life. A stable axis tilt angle is necessary for life—not sufficient.

This must be true. As shown below, when we take the contrapositive of the conditional claims in the stimulus, we see that the absence of the Moon would mean the Earth would be unable to support life. In other words, the Moon is necessary for Earth’s ability to support life.

This could be false. A stable axis tilt angle is a necessary condition for a planet’s ability to support life—not a sufficient one.

This could be false. While the stimulus focuses on moons and their impact on the planets’ axis tilt angles, it does not suggest that moons are the only important factor affecting the planets’ axis tilt angles.

This could be false. We know Mars has very small moons and cannot support life. Given the information in the stimulus, however, it could be true that a planet has multiple moons with at least one large enough to keep the planet’s axis tilt angle stable.