I think it is the 3rd answer choice.
Answer:
in regions where the temperature often drops below freezing at night
Explanation:
Dark Matter only: detected through its gravitational attraction, has mass, most common form of mass in the halo of the Milky Way Galaxy, likely to consist of subatomic particles
Dark Energy only: inferred to exist from the measured acceleration of the universe's expansion, the proposed source of a universal repulsive force
BOTH: the universe contains more of this than it contains matter made from atoms, we do not know what it is made of
NEITHER: blocks light from stars behind it, "dark" because it emits only infrared light
Natural elements typically erode ancient ( and all ) buildings and structures overtime. That and an increasing amount of tourist attraction also doesn’t help the decaying... well everything. An article from the guardian supports this and even says that last year the EU threatened to remove the funding of the Great Pompeii Project which conserves and restores this ancient site.