The correct answer is option 3, which states that "The Islamic Calendar is twelve days shorter than the Gregorian Calendar." and "The Gregorian Calendar is a solar calendar." are correct.

1. The Islamic Calendar: Indeed, it is a lunar calendar and around 12 days shorter than the Gregorian Calendar. This difference is because the Islamic or Hijri Calendar has 354-355 days based on the lunar cycle, while the Gregorian Calendar has 365-366 days based on the solar cycle.

2. The Islamic Calendar started: This statement is incorrect. The Islamic Calendar did not begin in AD 632, it actually began in 622 AD which marks the Hijri era or the Prophet Muhammad`s migration to Medina from Mecca.

3. The Gregorian Calendar: The statement is true as the Gregorian Calendar is a solar calendar. It`s the most widely used calendar system today, consisting of 365 days in a year, with a leap day every four years.