What was the age of Rasool Ullah (P.B.U.H) at the time of First Wahi?

What was the age of Rasool Ullah (P.B.U.H) at the time of First Wahi?

A. 40 Years 6 months
B. 40 Years 8 months
C. 40 Years 10 months
D. 40 Years 11 months