C/N, A(Li), and metallicity as a function of age (upper, middle, and lower panels), estimated with MIST evolutionary tracks (blue and red lines for stars A and B, respectively). The green bars show the Li content expected in star A after ingestion of planetary material. The values measured for stars A and B are shown in blue and red (including the error bars on the y-axis). The left panels correspond to the RGB phase, and the right panels correspond to the RC phase.