Which statement correctly describes a difference between the Roman and Gregorian calendars?

The early Roman calendar begins after the Gregorian calendar begins.
The early Roman calendar has more months in each year than the Gregorian calendar.
The early Roman calendar is based on the moon, while the Gregorian calendar is based on the sun.
The early Roman calendar starts with the birth of Jesus, while the Gregorian calendar is tied to the city of Medina.