The answer is A, C & D make no sense. B is not wrong, but A is the better answer.
To teach people who to live good Christian lives. They taught people about generosity and kindness
Answer:
Battle of Tannenberg, (August 26–30, 1914), World War I battle fought at Tannenberg, East Prussia (now Stębark, Poland), that ended in a German victory over the Russians. The crushing defeat occurred barely a month into the conflict, but it became emblematic of the Russian Empire's experience in World War I.
Explanation:
The leaders who spread Islam after Muhammad's death were Abu Bakr, Umar, Uthman, and Ali. If you want the answer from a website, I suggest going here
--> http://peopleof.oureverydaylife.com/led-islamic-world-after-muhammad-died-7743.html <-- I hope this answer helps you.