Błędnie: Sally's parents simply disprove of her decision and aren't going to help her in any way. Poprawnie: Sally's parents simply disapprove of her decision and aren't going to help her in any way.
"Disapprove (of)" oznacza ' dezaprobować', 'nie aprobować', 'nie pochwalać'; "disprove" to 'odpierać', 'obalać' (np. teorię, twierdzenie).