The answer to your question is B. Make and use fire
I'd say the combustion engine, even though it was toyed with in the mid-west during the cowboy era, it wasn't until after the Civil War in which it was a fully effective gasoline powered engine.
The sisters Sarah and Angelina Grimké primarily worked to end slavery, although they were also active in the world of women's suffrage. Abolition, however, was their greatest cause.
Answer:
William Becknell and George Sibley.
