a) The P-C relation in (B − V) of P0 Cepheids in both the very metal-poor SMC and the relatively metal-poor LMC relative to the metal-rich Solar neighborhood. b) Same as a) but for (V − I). c)–e) The P-L relations in B, V, and I, respectively, of the P0 Cepheids in SMC and LMC relative to the Solar neighborhood. The artificial spikes of the relations are due to statistical errors of the fits below and above the break. The lines are only drawn over the period range where they are well defined by observations.