Welcome to Cocoontech. Most of the time it will be Normally Closed. Do you have any tools like a multimeter (even a cheap one)? Or do you have access to the 'programming' of your alarm panel? Those would be the most sure ways to confirm but if you don't we can get creative with other possibilities. But I'm pretty confident it will be normally closed.
Thanks for answering. I have a multimeter, but not much experience using it. I looked at the alarm panel programming, but nothing jumped out as an answer. It uses acronyms of both "NO" and "NC" related to the zones, but nothing that clearly said whether it used "closed" or "open" circuitry.