Which calendar first divided dates into two categories,
b. c. and
a. d. ?
a. julian calendar
b. hebrew calendar
c. gregorian calendar
d. common era calend

The correct answer is C. The calendar that first divided date into two categories, BC and AC, was the Gregorian calendar.

Explanation:

The Romans counted the time with different computations. One of them was to start counting from the year of the founding of Rome, that is, ab urbe condita, abbreviated AUC. Another modality was the consular system and the so-called provincial eras, such as the Age of Diocletian, the Caesarea Age of Antioch or the Hispanic Era that began in 38 BC.

In the Christian era, with Pope Boniface IV in 607, the origin of the scale became the birth of Christ. A Romanian monk, Dionysius the Meager, based on the Bible and other historical sources, dated the birth of Christ on December 25, 753 AUC. This year happened to be the year 1 AD, Anno Domini, year 1 of the Lord, but the years before this were still AUC. Finally in the 17th century were named the years before 1 AD as years before Christ, BC, and the later ones are years after Christ, DC.

When the account of the Christian era began, the mathematical concept of zero did not exist and the years were counted ordinally (that is: first year, second, etc.). The origin of the Gregorian calendar, then, is January 1 of the first year (year 1 AD).

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