Explanation

A is incorrect because Hazrat Abu Bakr did not institute the second Azan. B is incorrect because Hazrat Umar did not add this specific Azan. C is correct because historical sources state that during the caliphate of Hazrat Usman (R.A), the growing population of Medina led to the addition of a second Azan at Jumu'ah prayers. D is incorrect because Hazrat Ali did not introduce this practice.