What is the Gregorian calendar? What major turning point is highlighted in the Gregorian calendar?

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Explanation:

The turning point that is highlighted in the Gregorian calendar is the synchronization of the calendar with the solar year

The Gregorian calendar is the calendar used in most of the world. It is named after Pope Gregory XIII, who introduced it in October 1582. The calendar spaces leap years to make its average year 365.2425 days long, approximating the 365.2422-day tropical year that is determined by the Earth's revolution around the Sun.

answer; collective security;

the declaration states, “we hold these truths to be self-evident, that all men are created equal, that they are endowed by their creator with certain unalienable rights, that among these are life, liberty, and the pursuit of happiness….”