In the story of Ruth, what legal and cultural practice allowed Boaz to redeem Ruth and Naomi's family land, ensuring their security and continuing the family line?

A The role of kinsman-redeemer, allowing a close relative to redeem family land and marry a widow. B The practice of levirate marriage, requiring a close relative to marry a widow. C The right of firstborn son inheritance, granting him control over family assets. D The Jubilee year provision, allowing for the return of land to its original owners.