Nice and challenging quiz! While Q10 is technically correct as it is the only one that fits, perigee is not limited to the closest point of the Moon to the Earth in its orbit. Any object orbiting the Earth has a perigee at the point where their orbit brings them closest to the Earth, manmade or natural. "When an Earth-orbiting object is closest to the Earth on its orbital path" would be a better phrasing, although you can also leave it as is as it also holds for the Moon :)