In his old age he became a communist and during the cold war it was just too tough to be a communist in the US. He went to Ghana after it became the first African country. DuBios has worked for African independence all his life, and was invited to enjoy it by Kwame Nkrumah, his old friend, and Ghana's first president.
I believe your answer is C.
Hope this helps!
Gutenburg's printing press was such an important invention, because before he invented it, people would either write stuff all by hand, or make some stamping system. If Gutenburg hadn't invented the printing press, we wouldn't have printers to print things out!
Extra:
Gutenburg designed the printing press in a town called Strasbourg, France. he built the actual thing in Mainz, Germany.
