Final answer:
The characteristic that is NOT commonly shared among prehistoric ritual sites is the lack of ceremonial artifacts, as these locations often contain such items.
Step-by-step explanation:
The characteristic that is NOT a commonly shared feature of prehistoric ritual sites is c. Lack of ceremonial artifacts. Prehistoric sites often have a connection to celestial events, are aligned with natural features, and sometimes utilize megalithic structures.
Many prehistoric sites indeed exhibit alignments with significant celestial events such as solstices or appear to be connected with natural phenomenons and landscapes. Megalithic structures like Stonehenge are typical examples of ritual sites with such features. However, these sites often contain ceremonial artifacts which suggest they were used for rituals or spiritual practices, debunking the idea that they lacked such artifacts.