  We argue that the measurement of open charm gives a unique opportunity to
test the validity of pQCD-based and statistical models of nucleus-nucleus
collisions at high energies. We show that various approaches used to estimate
D-meson multiplicity in central Pb+Pb collisions at 158 A GeV give predictions
which differ by more than a factor of 100. Finally we demonstrate that decisive
experimental results concerning the open charm yield in A+A collisions can be
obtained using data of the NA49 experiment at the CERN SPS.
