What was the center of politics in new england

What would lead a historian to consider two events to have a relationship of correlation rather than causation?

Which statement describes an important outcome of the congress of vienna? a. napoleon launched his final european military campaigns. b. european states had their borders clearly defined. c. jewish people were given equal right in germanic states d. the slave trade became increasingly important to european economies.

What is the relation between the hover dam and the gold rush