In the book of Ruth, beyond the love story, what legal and cultural practice is central to understanding Boaz's actions regarding Ruth and Naomi's inheritance?

A The law of gleaning, which allowed the poor to gather leftover crops. B The practice of levirate marriage, ensuring the continuation of a deceased man's family line. C The custom of offering hospitality to strangers and travelers. D The tradition of selling land to foreigners in times of economic hardship.