Do you know where to go to exercise your options? That would be a good place to start, and would by necessity allow you to see what your strike price is.
Though generally speaking, the strike price should be whatever the share price was on the date your options were granted. That may be easy information to find out, or impossible, depending upon if we're talking about a startup here or a more established company. I'm assuming the latter, because typically a startup would issue shares rather than options.
Anyways, if your strike price is low enough the safest bet (if you're dead set on not discussing the matter with your employer) would simply be to 'exercise and hold' them. That would require you to put up enough cash to cover the value of the options at the strike price, but would leave you holding shares rather than options. Which in general means that you will be treated the same as any other shareholder in the acquisition process (required by law in many countries, though as always check with a local lawyer to confirm).
Although don't rule out discussing the subject with your employer entirely. In general, that is the best way to get clarity on this sort of issue. I assume that you're probably not the only employee who has questions on the subject of the acquisition, and also probably not the only employee who has been given unclear information about their own options/equity situation.
It may be worth gathering the people who fit into either of those categories and having a joint meeting with the CEO to sort out all the questions and concerns that people have. It's harder for a potentially unscrupulous CEO to come up with an arrangement that's entirely in their own favor if half the company is on hand to call them out on it. If you're in a location where it's legal to surreptitiously record a private conversation (again, check with a local lawyer) then by all means do so for the sake of posterity. Then you at least have some possibility of recourse if the company does something that's different than what's discussed.
Next time around, definitely make sure that you've got a written equity agreement that spells out things like your vesting schedule, the strike price (when dealing with options), what happens in the event of an acquisition, and similar matters. Reputable companies will provide all of that information up front as part of standard operating procedures. Companies that don't are either disorganized or unethical.