D because it is in our human rights that they cannot do that
They did it because the current calendar and the system was related to religious motives and the monarch's rule. They removed all religious allusions and names as well as the names of kings from France's history and made it a secular calendar, while implementing the metric system and decimalising everything.
People were spending money they didn’t really have (due to credit being a new thing) and everything was basically a party until 1929