  We study the $B^0$ decay to $D^0 \bar D^0 K^0$ based on the chiral unitary
model that generates the X(3720) resonance, and make predictions for the $D^0
\bar D^0$ invariant mass distribution. From the shape of the distribution, the
existence of the resonance below threshold could be induced. We also predict
the rate of production of the X(3720) resonance to the $D^0 \bar D^0$ mass
distribution with no free parameters.
