In which ways have humans impacted the geography in the United States and Canada? Can someone please help me with get the correct answer

Ascientist is explaining how background cosmic radiation gives evidence of the big bang theory. she says that radiation has been detected everywhere equally as heat in the universe and is increasing. this has been shown to be residual radiation from the big bang. what error did the scientist make?

b) is there any ordinal sense to zip codes? in other words, does a larger zip code tell you anything about a location compared to a smaller zip code?

Can you give an explanation of what medc and ledc are.