The Hijri Calender was innovated by:

ہجری کیلنڈر کا اختراع کس نے کی۔

Hazrat AbuBakar (RA)

Hazrat Ali (RA)

Hazrat Usman (RA)

Hazrat Umar (RA)

None of these

Before advent of Islam, the calendar year in Arabia was: Anno Domini

Islamic Calendar starts from: Hijri

Islamic calendar established by: Hazrat Umar (R.A)