What type of calendar was used in Egypt to mark the flooding of the Nile?

The correct choice reflects the use of a lunar calendar in ancient Egypt, which was integral to their agricultural cycles and rituals. The Egyptians relied on the phases of the moon to measure time, as this was directly linked to the natural rhythms of their environment, including the annual flooding of the Nile River. This flooding was crucial for agriculture, providing fertile soil for planting, and thus needed to be tracked accurately.

The lunar calendar allowed them to predict the flooding cycle effectively, as it demonstrated the ebb and flow of natural phenomena. This correlation between the lunar cycles and agricultural activities was vital for a society dependent on such events for its survival and prosperity.

The other options do not align with the Egyptian practices at the time. A solar calendar, while useful, does not reflect the primary reliance on lunar phases in ancient Egyptian society. A lunisolar calendar combines elements of both lunar and solar measurements, which could also be utilized in various ancient cultures but was not the primary system in Egypt. The Gregorian calendar, on the other hand, is a more modern system developed much later and does not pertain to ancient Egyptian chronology.