Why is it important for nations to economically specialize?

Which statement is a good description of a model? a) models are a description of nature based only on one or two variables. b) models are testable ideas but they are not very to most people. c) models are a description of nature that predicts more accurately than real events. d) models are an approximiation of a real system that omits all but most essential variables in a system.

What trade did europeans want most before the 1800s ivory wood slaves gold

Anthropologist ralph linton said, "the last thing a fish would ever notice would be water." what does this imply about culture