Studying proton-proton scattering at 7 TeV, the ALICE collaboration found the unexpected result that the D meson multiplicity increases more than linear as a function of the charged particle multiplicity. We try to understand this behavior using the EPOS3 approach. Two issues play an important role in this context: multiple scattering, in particular its impact on multiplicity fluctuations, and the collective hydrodynamic expansion. These data contain
therefore valuable information about very basic features of the reaction mechanism in proton-proton collisions.