One of the greenhouse gases(GHG)is carbon dioxide .explain how increase in the amount of carbon dioxide in the atmosphere causes global warming

If a particular resource is not useful or needed then the price would be considerably low. once that resource is needed the price or value will raise depending on how useful or needed it is especially if the resource is low in quantity, the consumers would pay whatever they have to, to get that material.

The traditional economy

Hello there.

evidence that early humans migrated from asia to north america was found in alaska and  
b. siberia 

Idon’t understand that