Predicted [C II] PS. Left: Δ²(k, z ≃ 3.6) computed in the CDM scenario for our optimistic (solid red line) and pessimistic (solid blue line) cases for α = −1.1. The shaded areas represent the associated statistical uncertainty as for our survey reference setup. The dotted line is a graphical representation of the white-noise level, P_WN, while the dashed and dot-dashed lines refer to the clustering and shot-noise components, respectively. Right: ratio between the WDM and CDM power spectra. The dashed and dotted black lines correspond to WDM models with m_WDM = 10 keV and 0.5 keV, respectively. The shaded regions reflect the CDM uncertainties from the left panel. In both panels, the markers illustrate the adopted binning scheme.