Which is the most sacred month in Islamic calendar?

1. Muharram ul haram
2. Ramadan ul Mubarak
3. Rabi-ul-Awal
4. Zil-Hajj

Dhul-Hijjah is the holiest month in Islam. It is the month during which the Hajj pilgrimage is performed. The Day of Arafah and Eid al-Adha also occur in this month.