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

When presenting a list (or series), a comma is needed after each list item of a list containing three or more elements.  The comma is also needed after the element that precedes the conjunction before the final element.  This type of comma is called the “serial comma” or “Oxford comma.”  As such, the third sentence is the sentence that correctly uses commas to separate items in the list.