Which term is described as a shelf of undersea land reaching a depth of 200 meters?

Using complete sentences, describe the central economic problem facing all humans. why does this require people to make choices? how can this result in opportunity costs?

Suppose you had to resolve the problems believed to be caused by distance decay in russia. what would you suggest?

Put these ecosystems in order of least biodiversity to most biodiversity 1. mediterranean forest 2. indonesian rain forest 3. arctic ocean