TL;DR Choose the two options that matches your view in most cases(not B0nk skullcrusher smash to head, but the average ingame death)
Long description
I'm curious on what you think being reduced to 0 hp means. My own view is that: being reduced to 0hp(death) is equal to being defeated for the remainder of the round.
On EU1/EU2 Siege: Injury that stops you from being able to participate for at least 7 min.
On Conquest maps: it's the identical reasoning but round time limit(15-45min) instead of 7 min
My choice: 3&4
Edit: Fixed topic title, many of the early posts are correctly befuddled by my lack of proofreading before posting pointing out my poor topic title typing skills