¹⁶O/¹⁷O ratios after the first dredge-up versus stellar mass in M_⊙. Lines represent the theoretical predictions, and the red squares are observations. Blue solid line: reference model (R). Blue dashed lines: ¹⁷O proton capture rate modified within the suggested upper and lower rates (O17L and O17H). Solid black line: theoretical predictions as obtained by reducing the initial ¹⁶O to [¹⁶O/H] = –0.22 (C16OL).