But note that treatment and age can cause the pine to become harder. So even if it doesn't dent easily with a fingernail, I would still think it's pine.
Another vote for pine. That said, I think that pine gets a bit of a bad rap. Other than its softness, it's a fine wood to use. I have pallet and firewood laminated desk that has it's fair share of pine in it and the pine strips are not any worse for wear than anything else.
I think I'm leaning toward pine as well. You could cut into it and smell, I imagine most people now the scent of pine since it's a popular air freshener/household cleaner scent for some reason (I'm from a pine forest, pine doesn't smell 'clean' to me.)