In the story of Ruth, what legal custom allowed Boaz to redeem Naomi's land and marry Ruth, thus ensuring the continuation of Elimelech's family line?

A The law of gleaning, which allowed the poor to gather leftover crops. B The levirate marriage, which required a brother to marry his deceased brother's widow. C The law of redemption, which allowed a close relative to buy back property and family members sold into slavery. D The jubilee year, which returned all land to its original owners every 50 years.