It is almost always the case that you could argue either side of any issue they present to us. Technically (according to the rules), you can discuss both sides if you want to.
I strongly recommend that you do NOT do that, however. Your goal here is to get a "good enough" score using as little brain energy as possible (because the essay score isn't very important).
It's FAR easier to pick one side, think of two examples to support that side, and be done with it. If you try to support both sides, you will have to figure out under which circumstances it's better to do X, then describe and provide examples to support, and under which circumstances it's better to do Y, then describe and provide examples to support. No thanks.
They don't care what you actually think. Nobody's going to come back to you in a year and say, "in your GMAT essay, you said..." :)
This article can help you more:
http://www.beatthegmat.com/mba/2009/12/30/ace-the-essays-no-thanks