Question

Which sentence correctly uses commas to separate items in a list? The deacidification process preserves pages by neutralizing acid with magnesium oxide, raising the pH level of the paper, and, minimizing the alkaline reserve. The deacidification process preserves pages by neutralizing acid with magnesium oxide, raising the pH level of the paper and, minimizing the alkaline reserve. The deacidification process preserves pages by neutralizing acid with magnesium oxide, raising the pH level of the paper, and minimizing the alkaline reserve. The deacidification process preserves pages by neutralizing acid with magnesium oxide, raising the pH level of the paper and minimizing the alkaline reserve.

Answer 1

Technically speaking it could be either of the last two, but I believe at a High School level it would be looking for the third one becasue that's what is typically taught. 

And three works becasue it separates each of the 3 things and unlike 2, the comma is placed before the "and" 

One is wrong because it has a comma before and after the "and"