If Robinson Crusoe can, either shoot five wild geese or catch fifteen fish, on average, for each hour of labour effort. i.e. the opportunity cost of shooting one wild goose is three fish.
Since he lives by himself, the frontier limits his consumption of fish and geese. Apart from trade with natives, can you think of one factor that can change the opportunity cost? Please explain.
Opportunity cost is the next best alternative which the person is foregoing. As per econlib, "opportunity cost" of a resource mean the value of the next-highest-valued alternative use of that resource."
If Robinson ...
The solution discusses the opportunity costs are examined. A reference is provided to aid in the understanding of the solution.