Answer:
Correct answer is About 300 unarmed Native Americans were killed by armed U.S. soldiers.
Explanation:
First of all last two options are not correct as the Natives were killed, not the soldiers or 49'ers. Therefore it could be the first or second options.
The correct answer is the first option as the once that committed this crime against Natives were the members of 7th Cavalry.
It is regarded as one of the worst crimes in the history of United States against the Natives.
