The relationship between D_n4000 and Hδ_A, where the color coding for the different stellar-mass ranges follows the same scheme as in Figure 7. The first panel shows the results for the original sample, while the second panel presents results for a mass-matched sample. The third panel illustrates results matched for both M_* and SFR, and the fourth panel displays results for a mass–SFR–size-matched sample. Due to the limited number of galaxies satisfying the mass–SFR–size matching criteria, the fourth panel is not binned by stellar mass.