Many thanks to the referee for the review of the first draft,
and the suggested modifications. Apologies also for the
delayed response, partly caused by the Lufthansa pilot strike.


Regarding the first point, here I would prefer to leave the
caption of Fig.5 unchanged. Although certainly already the
(10-20)% activity bin is (almost) completely useless, as the
plot shows, the actual saturation in the number of hits
occurs only in the (0-10)% bin.

The second point is indeed a piece of valuable information,
as it implies that the D0 measurement really is a clean probe
of open charm. Thanks for pointing this out. The revised
text reads:


"Since the products of a breakup of a charmonium state most likely will
recombine to open charm mesons, charmonia and open charm mesons are 
affected differently by the transport properties of the nuclear medium. 
Additional information is therefore gained from the study of \Dz\ 
production in  $p$-Pb collisions [13], which because of the small
charmonium to open charm ratio will not be measurably affected by
contributions from charmonium break-up. Figure 4..."