Answer:
photchemical smog
<em>hope</em><em> </em><em>this</em><em> </em><em>helps</em>
You mentioned "...following statements" in your question. But where are the statements?
From an archived question I looked up for you, I believe it should be water-table aquifers. By the way, if you look in the link above, replace the 4449929 with 482974 to see the answer to it!