The correct answer should be <span>unification of previously fractious and divided Arab tribes
Many Arab countries were angry because the Byzantine empire tried to impose Christianity on them. They responded by joining together under the banner of Islam to spread and stop Christianity. This started in the 7th century and Muslims managed to win places like Persia, Syria, Egypt, and unite in order to push the Byzantines back.</span>
Answer: I was a preventative mesuare against polio
Explanation:
Polio is a virus that caused muscle weakness. Although most people fully recover it became a big problem in the US. That is what the vaccine was created. You could say it saved America.
This was called the Great Trek
For profits. Less money going towards cleanliness and safety, and wages = more money going towards profit.