Answer to Question 1
Mercury's rotation axis is almost perpendicular to its orbit. This means the angle of the Sun with the southern (or northern) horizon never changes. On Mercury, an observer at the equator would always see the noon Sun overhead, an observer at the pole would always see it on the horizon. On Earth, the altitude of the Sun changes over the year because of the 23.5 degree axial tilt.
Answer to Question 2
D