Who added the phrase “Assalatu Khairum Minan Naum” to the Fajr prayer?

(A) Hazrat Abu Bakr (R.A)
(B) Hazrat Umar (R.A)
(C) Hazrat Usman (R.A)
(D) Hazrat Ali (R.A)

The answer is: (B) Hazrat Umar (R.A)