I believe it would be b. Eastern Orthodox.
Well the cause of a certain event in history will mean something happens.
The effect is the result of the event happening
For example. With 9/11 the cause was the twin towers collapsing. The effect would have been thousands of people dying as the result of the planes being highjacked
After spending the winter in Vinland, Leif sailed back to Greenland, and never returned to North American shores. He is generally believed to be the first
