Admin. Note (11/8/2019)
Edited to add: Please see the following update by @"David.Busis" (also in Comments)
"Hey everyone—I can speak for @"J.Y. Ping" when I tell you that this advice from six years ago is no longer valid.
The writing sample matters.
Some admissions officers read all writing samples as a rule; some only read it for certain applicants under certain circumstances. Regardless, it matters. If the admissions team might read it, you have no choice but to act as if they will read it."
It doesn't matter. It's not a part of your score. Do it according to instructions and you'll be fine. I'm not really convinced that admissions officers even read the samples. Seriously, who can still read handwriting?
The setup will ask you to make an argument, so make an argument. You will argue that out of the two options to pursue, one is better than the other. What metric do you use to argue for "better?" The setup gives you two goals, constraints, metrics, whatever you want to call it, that's how you argue for "better."
Make arguments for both sides. But, ultimately argue for just one side.
For example, we need to get off the island. We have two options: bridge or ferry. We have two constraints/goals/metrics: safety and speed.
Argument: We should take the bridge. The bridge is safer and faster. Some people think the ferry is safer and faster but they are idiots. They make arguments like X, but, come on. X, really? That's all you got? Come on. So, we're in agreement, yes? Off to the bridge!
The above satisfies the instructions, but is a very bad argument. Imagine if that's on an LR section. You'd tear that argument to pieces! So, make sure you don't make arguments like that one. Call out any assumptions you make, e.g., "I presume blah blah blah is the case." Don't make fallacies, e.g., attacking an argument with "Come on."
Anyway, by the time you get to this section, the test is pretty much over and you should feel overwhelming relief. So, try to have some fun with it! :)