Variation in [OIII]/[OII] with Σ_SFR. Individual galaxies with detected [OII] are shown with red and blue symbols for the C3-VUDS and C3-VANDELS samples, respectively. We also include lower limits based on the upper limits on [OII]. The small green and magenta circles are galaxies from Reddy et al. (2023a) at z = 1.6 − 2.6 and Reddy et al. (2023b) at z = 2.7 − 6.3, respectively. The solid black line is the relation presented in Reddy et al. (2023a), and its extrapolation up to Σ_SFR = 100 M_⊙ yr⁻¹ kpc⁻² is plotted as the dashed black line.