All four work for me.

Also: quit:quit, slit:slit, set:set, put:put. Perhaps a rule might be that if it ends in "t" then the plural is the same as the singular.

Official ruling? Do we have a National Academy as they do for Spanish?

Text will probably go regular in the past tense i.e. "texted" but the past tense could also easily be "text." as in the past tense of other verbs ending in "t": burst:burst, cut:cut, cost:cost, cast:cast, bet:bet. The tendency seems to be to make words regular - note the use of "mouses", not "mice" for more than one computer mouse.