In Hazrat Abu Bakr's era the siege of Damascus by Muslim Army was started on ______?

حضرت ابوبکر کے دور میں دمشق کا محاصرہ مسلم فوج نے ______ کو شروع کیا تھا؟

21 August 634 CE

20 August 634 CE

21 August 635 CE

None of these

The siege of Damascus (634) lasted from 21 August to 19 September 634 before the city fell to the Rashidun Caliphate.