The gemoro often reconciles the argument of a mishnah with other evidence by saying חסורי מיחסרא והכי קתני - there is something missing from the mishnah and this is how you must learn it. See for example Shabbos 37a at the top.
How do we understand this idea of something missing from the mishnah?
Could it mean
(a) “the mishnah is taught in a short form to make it easy to remember and if you examine it, it is obvious that something is lacking” or
(b) the mishnah is actually lacking a bit
or (c) some other explanation?