Answer:
Is there an article or text u can copy paste from??
Explanation:
One of the most significant challenges is building an airplane had to do with "propulsion", since the technology that allowed motors to have enough energy to lift an airplane into the sky with a passenger wasn't available for most of history.
Washington DC is the capital of the U.S.
The answer might be c) Jose Marti
Pretty sure your answer is B. They didn't get equal rights until the 60's, I don't believe they were removed from jobs, and I'm fairly certain they wouldn't have done work without pay (The Great Migration is a good example of that).