None of the above,
It's been a few months since I was at Denver, but I'll try to help answer your question.
There are 3 northerly runways at KDEN -- 35L, 35R, and 34R -- with a 4th (34L) under construction. Here's a link to a relatively recent airport diagram (with the usual disclaimer that it's not to be used for real-world navigation, etc.)
http://www.naco.faa.gov/content/naco...ms/09077AD.pdf
There are instrument approaches available to all three of these northerly runways, as well as the other runways there too, I'm pretty sure -- (sorry, my approach plates are not at home for me to reference directly).
If I remember correctly, arrivals are often made on 35L and 35R, with departures on 34R. This is just a technique, though, and can be modified as necessary, so it would be difficult to say which runway your aircraft used for landing.
However, if the weather is good, you don't necessarily need an instrument approach. At most airports (not just KDEN), visual approaches can be helpful to both pilots and controllers, so they may be used to
any open runway, any time weather and traffic conditions permit.
In case you want to know more about visual approaches, here's some additional info:
Visual approaches can vary greatly in their appearance -- for example, sometimes it's a downwind leg with a 180 turn to final; sometimes a simple base- or dog-leg to final -- the whole point is that when the pilots have the airport in sight and are cleared for a visual approach, they are given the freedom (within reasonable limits, of course) to visually align themselves for the landing. Because it's not as "defined" of a flight path, it gives the pilots and controllers much more flexibility. It's a great tool, and it makes a lot of sense when the weather is good.
Hope this helps.