If the Species in a Classification System Are Not Jointly

If the species in a classification system are not jointly exhaustive, can we fix the system by adding a species called "others"?

A) Yes, this is a good way to tie up the loose ends.
B) Yes, but this sort of solution should be avoided.
C) Yes, but only if the remaining referents are very similar to each other.
D) No, because then the species will not be mutually exclusive.
E) No, because this will put too many referents under a single species.