Astream has a source at an elevation of 1,000 meters. it ends in a lake that has an elevation of 300 meters. if the lake is 200 kilometers away from the source, what is the average gradient of the stream?
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gradient = change in value / change in distance

Cpopulation density

The answer is c, i, iii, and iv. this is because farming and mining deal with harvesting raw materials, construction work falls under manufacturing, and piloting a plane is a service. ii is wrong because making bread is using  raw materials to produce goods, which would fall under the secondary sector, not primary.