Final answer:
The priority nursing diagnosis during the postpartum period when a woman stops breastfeeding suddenly and experiences breast engorgement and leakage is 'Risk for ineffective breastfeeding'.
Step-by-step explanation:
The correct priority nursing diagnosis during the postpartum period when a woman stops breastfeeding suddenly and experiences breast engorgement and leakage, just like in the first few weeks of breastfeeding, would be d) Risk for ineffective breastfeeding. Breast engorgement and leakage can indicate that the breasts are not being effectively emptied, which can lead to decreased milk production and potential breastfeeding difficulties.