Left panel: variations of the best-fit propagation parameters D₀ (blue) and δ (red) relative to the benchmark values of Table 1, as a function of the primary boron-to-carbon injection ratio. The reference model corresponds to the conventional no boron hypothesis for which N_B/N_C vanishes. Right panel: the theoretical value of the B/C ratio at 214 GeV/nuc (solid red curve) is plotted as a function of the primary boron-to-carbon injection ratio. The dashed black curve indicates the goodness of the B/C fit. As long as N_B/N_C does not exceed 13%, the theoretical B/C ratio is within 2σ from the AMS-02 measurement (dashed-dotted green curve).