Explanation

D is correct because Khalid bin Waleed (R.A) was famously given the title 'Sword of Allah'. A is incorrect because Abu Bakr Siddique (R.A) was known for his piety and companionship. B is incorrect because Umar Farooque (R.A) was known for his justice and strength. C is incorrect because Ali Al-Murtaza (R.A) is not associated with this title.