acho que não

A or B, depending. Much hinges upon whether or not the cow-orker is otherwise likeable. Though an alternative to A might be to say nothing up front but gossip and ridicule at the water cooler.

I'm petty that way.

Their breath must be pretty fricken rank if you can smell it from your house.

Tomato Nation dealt with this recently, I believe.

I think that the earnest discussion is the most honest and respectful way to handle the issue, but it also takes the most fortitude. Still, I would feel terrible if I loudly mocked or gossiped about someone only to learn that there was a genetic cause or disease or something involved.

Another vote for the "sack up and tell the person tactfully" plan. Awkward? Yes. What I'd like someone to do, were I halitosis-plagued? You bet.

It's also a good gut-check as to whether you're getting bent out of shape over nothing. Do you care enough about the problem/is it bad or distracting enough that you want to say something? If you want to chicken out and let Dragonbreath be, your best bet is to just get over it. (All of this is the hypothetical "you" of course. I don't feel like getting all "one could blah dee blah" in a blog comment.)

Initially when I read "gut-check" I thought it was a hockey maneuver.

In any case, that was some wisdom, Leems!

f) Offer mints. Or mint flavored gum. A couple times if needed. If the smelly doesn't catch on, have one yourself. It'll help.

Where I work, I would do d), but that's because of office politics and whatnot. Also, because it's offensive to others as well I'm assuming, the manager should know and do something about it in case it's a problem in the future. And this way, you can be cowardly about it if you like.