  We make predictions for the production and decays of $X(2900)$ states, and
their possible charged partners, in $B^+$ and $B^0$ decays, considering a
number of competing models for the states, including triangle diagrams mediated
by quark exchange or pion exchange, and resonance scenarios including molecules
and tetraquarks. Assuming only isospin symmetry and the dominance of
colour-favoured weak decays, we find characteristic differences in the
predictions of the different models. Future experimental studies can therefore
discriminate among the competing interpretations for the states.
