Answer: Steam power, which lead to steam powered ships helped European forces colonize Africa.
Explanation:
Steam Powered ships aren't the only thing though, and I think they're kinda tied in 1st place with guns for "Scientific advancement that most helped Europeans colonize Africa". I think-- I could be wrong, but I'm pretty sure-- they had machine guns at that point. Let me just double check that so I don't mess you up.
Yup! They had the maxim machine gun which "allowed Europeans to wipe out Africans in battle after battle."
Jeez. That whole time period was so messed up
It made Americans have less trust in their government
Your answer should be D hope this helps have a nice day