Temperatures on the Surface of Mercury Are Seen to Fluctuate

Temperatures on the surface of Mercury are seen to fluctuate between very cold 100 K (-173°C) and extremely hot 700 K (427°C) . What does this measurement indicate about conditions on Mercury?

A) Mercury has a very elliptical orbit, and varying distance from the Sun produces these large temperature fluctuations because intensity varies as the inverse square of the distance from the Sun.
B) The planet has an atmosphere in which the greenhouse effect captures solar radiation to heat the sunlit hemisphere of the planet.
C) The planet is close to the Sun, has no atmosphere to maintain heat from the Sun, and is rotating slowly.
D) Erupting volcanoes occasionally heat the planet's surface to extreme temperatures.