The calendar we use today is based on the________
A. Muslim era
B. Hindu era
C. Christian era
D. Parsi era

Hint: Presently we use the Gregorian calendar around the World. A calendar era is used to understand the chronology of time, the period of one year which begins on 1st January and ends on 31st December.

Complete answer: Today the calendar we use the most is called Gregorian calendar. This calendar is based on the Christian era. This is the calendar which is used most around the world. It has 12 months and 28-31 days approximately and 365 days. This was founded by Pope Gregory XIII, and it is named after him. The new calendar was a modified version of the Julian Calendar. In the new calendar the number of days in a year from 365. 25 days to 365.2425 days. The correction of the solar year was made which was inaccurate in the previous years. The reform was accepted by the Catholic countries. The Protestant countries and the rest also started using this calendar.
The undertaking of the Gregorian had two features:
1. It brought down the number of days in a year by 0.00075 days.So that the calendar did not change as per the equinoxes.
2.The calendar year is based on the notations of Common Era (CE)
Option C is the right answer.

Note: In the Julian calendar leap year happens every four years. In the Gregorian calendar 29th of February is regarded as a leap day. The protestant and the Orthodox churches were not ready to accept this calendar. However, they did accept it later on and today the Gregorian calendar is the universal calendar in the world.