There was more than one technology that was developed at the time, but one technolgoy that surely made a strong impact and also enabled Europe becoming the dominant military force was the invention and perfection of military tactics together with muskets and cannons. This made them practically unstopable against any native population around the world.
The massacre at Wounded Knee in 1890 occurred in response to "<span>d. the discovery of gold at Pike’s Peak" since this was the main reason why settlers were there, although this was not exactly a "response". </span>
I believe the answer is B
