Final answer:
The treasures from Alexandria's Royal Quarters are mostly intact because the palatial architecture was designed to provide structural stability against earthquakes, helping to preserve them during seismic events. So the correct answer is C.
Step-by-step explanation:
Many of the treasures from Alexandria's Royal Quarters are not broken because the palaces were built to sustain earthquakes. The architecture from this period included multiple entrances and a multitude of rooms, creating not only a protective façade but also providing structural stability during seismic events. This design was more than for fortification against attacks; it was also adapted for seismic activity, which was prevalent in the region. As indicated by historical evidence, the region experienced earthquakes, and thus buildings, including palaces, had to be constructed with these dangers in mind. This smart architectural adaptation helped preserve many treasures from being destroyed during natural disasters.