Within the narrative of the book of Ruth, what cultural practice does Boaz utilize to demonstrate kindness and fulfill his kinship obligation towards Ruth and Naomi?

A Levirate marriage, ensuring the continuation of the deceased husband's family line. B Gleaning rights, allowing the poor to gather leftover crops from the fields. C Redemption of property, buying back land that had been sold due to poverty. D Offering hospitality, providing food and shelter to strangers in need.