Abundance trends of D40 (green circle), local H II regions (gray diamonds), and low-metallicity dwarf galaxies (blue squares). Open blue squares represent dwarf galaxies without direct T _e [S III]. The ⊙ symbol denotes solar abundances from Asplund et al. (2021); the dashed orange line and shaded areas are the solar N/O, S/O, and Ar/O ratios. Top: log(N/O) vs. 12+log(O/H). Middle: log(S/O) vs. 12+log(O/H). Bottom: log(Ar/O) vs. 12+log(O/H). The first T _e -based S and Ar abundances at z ∼ 3 indicate subsolar S/O and Ar/O, suggesting that these three elements are sensitive to O/H or star formation history.