What should I donate on Kartik Purnima for maximum merit?

The scriptures identify three donations of maximum merit on Kartik Purnima: Deep Daan — offering a ghee lamp at a Vishnu temple or on the Ganges, which the Padma Purana says liberates ancestors; feeding cows with fodder and jaggery, earning the merit of cow donation; and Anna Daan — donating food to Brahmins or the poor. Among these, Deep Daan at Kashi is considered the highest.