I will look up most words I come across that I don't know if I can't figure out what they mean within the context of the sentence. It doesn't happen very often, and mainly with classics where words have fallen out of use.
One of the reasons I hated Captain Corelli's Mandolin was that for the first half of the book there were so many words I didn't know and couldn't understand what the author was trying to say, so I looked up the words, to find most of them had been out of use for decades and that their meanings didn't actually make sense within the context of the sentence anyway.
Can't really vote in the poll, as I fit somewhere between options 1 and 2