GMAT Sentence Correction (SC) | Re: In Ponoma College, a rule has been passed that permits

The important thing to note here is that once we have a hint of //ism being tested, we must decide the various arms of the //ism involved. There may be two arms or seemingly more than two arms and the last one of the series must be connected either by a conjunction‘and ’ or by a prepositional phrase such as‘as well as’.

In this case, three are three things listed i.e.,cook, serve and buy ; are they all independent actions?. No, not all;‘to cook and serve’ is one