Correct answer is option C.
The ground-level ozone is a harmful air pollutant that can be a danger to one's health. It is commonly created by chemical between oxides and nitrogen. Similar to ground-level ozone, smog can also be a danger to one's health, especially to the lungs. It is a mixed smoke and fog.
The roots of the human civilizations are mostly associated with the Asian continent because most of the early civilizations developed here, like the Sumerians, Persians, Phoenicians, Babylonians, Chinese, Hindus. These civilizations, especially the ones from the southwestern part of Asia, played a key role in the development of the civilizations along the Mediterranean in Europe, since they were borrowing culture, alphabet, math, lots of inventions, mythology etc. After their cultural traits were accepted in Europe, they started to spread around even more, and gave the basis for the development of lots of other civilizations.