When Hijrah started?

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When Hijrah started?

A. 12th Rabi-ul-Awwal of 13th year of Nabawat
B. 12th Rabi-ul-Awwal of 12th year of Nabawat
C. 12th Rabi-ul-Awwal of 14th year of Nabawat
D. 12th Rabi-ul-Awwal of 10th year of Nabawat