Promotion could have multiple meanings.
For example, if you say "Mr. Knight got promoted (or got a promotion) from supervisor to manager". There promotion means "raise".
If a product is at promotion there promotion means advertising efforts.
It could also refer to a way to support a cause. For example: There's a campaing supporting healthy lifestyle promotion.
I think it's B. A reason to go to a place.
Explanation:
In the late 1800s, people in many parts of the world decided to leave their homes and immigrate to the United States. Fleeing crop failure, land and job shortages, rising taxes, and famine, many came to the U. S. because it was perceived as the land of economic opportunity.