It would have to be b. natural rights
The Crusades is the series of wars between the two groups but if you're looking for a certain one I can further elaborate.
Answer:
Opportunity cost is the cost of the next-best option. It is something important to know.
Explanation:
In microeconomic theory, opportunity cost is the loss or the benefit that could have been enjoyed if the best alternative choice was chosen. As a representation of the relationship between scarcity and choice, the objective of opportunity cost is to ensure the efficient use of scarce resources.
Please mark brainliest.
They were both concerned about Russia because it was a large and influential country
