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What is the correct definition of an opportunity cost?

A.) a cost that varies depending on the choices made by a person or group
B.) a cost that does not increase or decrease regardless of how circumstances may change
C.) the cost of producing one additional unit of a good or service
D.) the cost of choosing to do one thing rather than choosing the next best option

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations