Take BC and be sure not to get any D’s. A few kids at my son’s school were frustrated with B’s they received in AB so elected to take Stats senior year instead of more Calc. They were rejected or accepted undeclared instead of getting their engineering majors at mid tier UC’s. Same goes for those who skipped extra physics for easier AP environmental science. Your child will be compared to peers who took the most rigorous STEM classes. She should present the strongest application possible unless she really struggled in AB.